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Rapid urbanization increases urban air temperature, considerably affecting health, comfort, and the quality of life in urban spaces. The accurate assessment of outdoor thermal comfort is crucial for urban health. In the present study, a high-resolution mesoscale model coupled with a layer Urban Canopy Model (WRF-UCM) is implemented over the city of Hyderabad (17.3850° N, 78.4867° E) to simulate urban meteorological conditions during the summer and winter period of 2009 and 2019. The universal thermal climate index (UTCI) has been estimated using the model-derived atmospheric variables and a human biometeorology parameter to assess the linkages between the outdoor environment and thermal comfort. Results revealed that during summer, the city experiences nearly 50 h of very strong thermal stress, whereas about 120 h of slight cold stress are experienced during winter. The urban area in Hyderabad expanded from 5 to 15% during the study period, leading to a 2.5℃ (2.8 ℃) increase in land surface temperature, and a 1.2 (1.9 ℃) rise in air temperature at 2 m height and 1.5 (2.5 ℃) UTCI during summer (winter) time. The analysis reveals that the maximum UTCI values were noticed over built-up areas compared to other land classes during daytime and nighttime. The results derived from the present study have shown that the performance of WRF-UCM-derived UTCI reasonably portrayed the significant impact of urbanization on thermal comfort over the city and provided useful insights with regard to urban comfort and welfare. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate which climate/heat indices perform best in predicting heat-induced loss of physical work capacity (PWCloss). Integrating data from earlier studies, data from 982 exposures (75 conditions) exercising at a fixed cardiovascular load of 130 beats·min−1, in varying temperatures (15–50°C), humidities (20–80%), solar radiation (0–800 W·m−2), wind (0.2–3.5 m·s−1), and two clothing levels, were used to model the predictive power of ambient temperature, universal thermal climate index (UTCI), wet bulb globe temperature (WBGT), modified physiologically equivalent temperature (mPET), heat index, apparent temperature (AT), and wet bulb temperature (Twb) for the calculation of PWCloss, skin temperature (Tskin) and core-to-skin temperature gradient, and thermal perception (thermal sensation vote, TSV) in the heat. R2, RMSE, and Akaike information criterion were used indicating model performance. Indices not including wind/radiation in their calculation (Ta, heat index, AT, and Twb) struggled to provide consistent predictions across variables. For PWCloss and TSV, UTCI and WBGT had the highest predictive power. For Tskin, and core-to-skin temperature gradient, the physiological models UTCI and mPET worked best in seminude conditions, but clothed, AT, WBGT, and UTCI worked best. For all index predictions, Ta, vapor pressure, and Twb were shown to be the worst heat strain predictors. Although UTCI and WBGT had similar model performance using the full dataset, WBGT did not work appropriately in windy, hot-dry, conditions where WBGT predicted lower strain due to wind, whereas the empirical data, UTCI and mPET indicated that wind in fact increased the overall level of thermal strain. The findings of the current study highlight the advantages of using a physiological model-based index like UTCI when evaluating heat stress in dynamic thermal environments. NEW & NOTEWORTHY: There is an urgent need to determine the optimal heat stress metric when forecasting the impact of heat stress on human performance, physiological stress, and perception. We analyzed a wealth of laboratory data, simulating heart rate (HR)-paced work with wide variations in air temperature, humidity, wind speed, solar radiation, and clothing. We conclude that the universal thermal climate index (UTCI) [followed by wet-bulb globe temperature (WBGT)] is the optimal heat index to reliably predict reductions in performance, and elevations in physiological and perceptual stress. [ABSTRACT FROM AUTHOR]

Abstract This study evaluates the applicability of three thermal comfort indices—Physiologically Equivalent Temperature (PET), Standard Effective Temperature (SET), and Universal Thermal Climate Index (UTCI)—in various outdoor environments on the campus of Xi’an University, China. Meteorological data were collected on sunny days using a portable weather station at a height of 1.5 m, and subjective questionnaires were administered to 25 healthy university students over three months to gather Thermal Sensation Votes (TSV) and Thermal Comfort Votes (TCV). The study was conducted at four distinct outdoor locations: a lakeside area (Location 1), a shaded path (Location 2), a sports field (Location 3), and a plaza (Location 4). PET, SET, and UTCI values were calculated from the collected data using Rayman software. The analysis revealed significant differences in thermal comfort across the four locations, with the highest proportion of subjects feeling hot at the sports field (54.4%) and the highest proportion feeling cold at the lakeside (39%). The shaded path had the highest proportion of subjects feeling comfortable (79.4%), while the lakeside had the lowest (60.1%). The results indicated that SET underestimated thermal sensation at Locations 1, 3, and 4, necessitating calibration. PET was suitable for Locations 2, 3, and 4 but failed to reflect the thermal sensation at Location 1 due to prolonged sun exposure. In contrast, UTCI demonstrated applicability across all locations. To enhance accuracy, revised indices SET’ and PET’ were formulated using the mean-median method, providing more precise thermal comfort assessments. These findings underscore the limitations of SET and PET under specific conditions and highlight the robustness of UTCI, offering valuable insights for urban planning and design aimed at improving outdoor thermal comfort and well-being.

Heatwaves and droughts increasingly impact public health and societal system in a world subject to global warming. Several studies reported these phenomena all around the world, but there is a dearth of research specifically in West Africa. This study fills that gap by comparing heatwave/heat stress and drought occurrence in three climate zones (Guinea, Sudan and Sahel) of West Africa from 1981 to 2020. The analysis focuses on the comparison of station and gridded datasets. The Cumulative Excess Heat (CumHeat) and the Universal Thermal Climate Index (UTCI) are considered for heatwaves. For drought, the Standardized Precipitation (Evapotranspiration) Index SPI (SPEI) are used at 3‐, 6‐ and 12‐month scales. Both heatwave and drought characteristics are investigated as well as their co‐occurrence (D‐HW). The investigation reveals a good correlation between station and gridded datasets for drought indices. While station data records fewer and less intense heatwave, gridded data indicates longer‐lasting heat extremes. The study also demonstrates a strong agreement between the UTCI computed from the Rayman model and ERA5‐HEAT dataset, despite timing discrepancies, especially along the Guinea coast. The Sahel region is found to endure higher heat stress levels, with increasing intensity of heatwaves over time. Notably, the study uncovers an increasing frequency of compound D‐HW in all zones, especially the Sudan and Sahel zones, offering new insights into the climatic challenges faced by West Africa. These findings emphasize the critical need for improved planning and early warning systems (EWS) to mitigate the impacts of these climate extremes ecosystems and human health. [ABSTRACT FROM AUTHOR]

The research on the thermal bioclimate is increasingly valuable in the context of climate change. Human well-being is threatened not only from direct exposure to extreme thermal conditions and complications from underlying health issues but also from disruptions of health and social services. This study aims at examining the thermal bioclimate in Greece. Data of ERA5-Land reanalysis dataset were used to estimate the Universal Thermal Climate Index (UTCI, in °C). The analysis covered a 30-year period (1991–2020) examining UTCI climatology and trends. Additionally, the intensity of two recent heatwaves which occurred in summers 2021 and 2023 was assessed. During the period 1991–2020, the UTCI equivalent temperature ranges between -49.8 °C and 51.9 °C [mean ± standard deviation (sd) = 13.3 ± 12.2 °C] classifying thermal stress from 'extreme cold stress' to 'extreme heat stress'. Across the country, the mean UTCI ranges from 7.5 °C to 17.8 °C (mean ± sd = 13.3 ± 2.1 °C), with a decrease of 0.5 °C per latitude degree. Mountainous regions exhibit the lowest UTCI equivalent temperatures, while inland plains display higher UTCI equivalent temperatures, especially in the eastern regions of the country. An increasing trend in mean annual UTCI (mean = 0.05 °C/year) is identified, more pronounced in higher latitude regions. Both the 2021 and 2023 heatwaves were exceptionally severe, with about 99% of the population to experience mean UTCI equivalent temperatures falling within stress categories of 'moderate heat stress' and above. The 2023 heatwave set a new record with the highest absolute maximum UTCI (52.1 °C) and number of heat stress hours compared to the period 1991–2020. The bioclimatic maps developed in this study analyze the spatial variability in the thermal conditions across Greece identifying high-risk areas. These findings can contribute to impact studies for tourism, energy efficiency, urban design and public health purposes. [ABSTRACT FROM AUTHOR]

This study concerns the application of statistical learning (SL) in thermal stress assessment compared to the results accomplished by an international expert group when developing the Universal Thermal Climate Index (UTCI). The performance of diverse SL algorithms in predicting UTCI equivalent temperatures and in thermal stress assessment was assessed by root mean squared errors (RMSE) and Cohen's kappa. A total of 48 predictors formed by 12 variables at four consecutive 30 min intervals were obtained as the output of an advanced human thermoregulation model, calculated for 105,642 conditions from extreme cold to extreme heat. Random forests and k-nearest neighbors closely predicted UTCI equivalent temperatures with an RMSE about 3 °C. However, clustering applied after dimension reduction (principal component analysis and t-distributed stochastic neighbor embedding) was inadequate for thermal stress assessment, showing low to fair agreement with the UTCI stress categories (Cohen's kappa < 0.4). The findings of this study will inform the purposeful application of SL in thermal stress assessment, where they will support the biometeorological expert. [ABSTRACT FROM AUTHOR]

The health of urban populations is increasingly at risk due to the amplification and chronification of urban heat stress by climate change. This is particularly true for urban environments in humid tropical climates, including many cities in Southeast Asia. It is also in these locations where increasing climatic risks may be exacerbated by urban growth, underscoring the need to develop effective mitigation strategies for strengthening urban resilience and supporting climate change adaptation. Conservation and widespread implementation of green infrastructure (GI) are regarded as one means to counter heat as a public health threat. However, for lower-income countries across Southeast Asia, such as Vietnam, knowledge gaps remain with respect to the effectiveness of greening interventions for heat mitigation. To address this gap, in the context of urban expansion in the humid tropical city of Huế, Vietnam, diurnal cooling potential and regulation of outdoor thermal comfort (OTC) within a wide, shallow street canyon were systematically assessed for selected elements of GI along a quantitative and qualitative dimension using ENVI-met. Tree-based interventions were found to be most effective, potentially decreasing UTCI by −1.9 K at the domain level. Although lower in magnitude, green verges and green facades were also found to contribute to OTC, with green verges decreasing UTCI by up to −1.7 K and green facades by up to −1.4 K locally. Potential synergistic cooling impacts were identified through a combination of GI elements. However, no scenario was found to decrease heat stress to zero or moderate levels. Substantially reducing heat stress may thus require further measures and a closer consideration of local morphological characteristics. [ABSTRACT FROM AUTHOR]

In this initial study of a research project, this paper seeks to understand the thermal conditions in the cities of Lisbon and Munich, specifically focusing on Urban Heat Island intensity and on thermal comfort using the Universal Thermal Climate Index modeling data at the Local Climate Zone scale. Based on these datasets, Munich has exhibited more unfavourable thermal conditions than Lisbon. In terms of UHII, both cities have shown that low, medium, and high rise compact urban areas and bare rock or paved areas have the highest values, while sparsely built areas have the lowest. These results differ from the UTCI, which indicates that in Lisbon and Munich, these sparsely built areas as well as areas with low plants and vegetation are the most uncomfortable. In Munich, the population was exposed to very strong heat stress, while Lisbon experienced strong heat stress conditions. Conversely, low, medium, and high rise compact urban areas and densely wooded areas in Munich, and scattered trees areas and large low-rise urban areas in Lisbon, have demonstrated the lowest monthly mean and average maximum values. These results will be further explored in future studies in the city of Lisbon and cross-checked with data obtained from roving missions. This will enable a more detailed temporal and local analysis. [ABSTRACT FROM AUTHOR]

Nigeria's growing population faces an increasing heat burden with potential health risks. The Universal Thermal Comfort Index (UTCI) links outdoor conditions and human well-being but lacks comprehensive insitu data in developing regions like Nigeria. ERA5-HEAT reanalysis offers a solution with gridded UTCI and MRT data, but validation is crucial. Thus, this study evaluates the ERA5-HEAT UTCI against data from nine Nigerian weather stations and analysed the spatio-temporal patterns of heat stress trends. Results showed that ERA5-HEAT demonstrated reasonable statistical performance and captured the temporal characteristics and patterns of UTCI across Nigeria's climatic zones. Seasonal variations show heat stress levels from ''slightly cold'' to ''moderate'' at 0600 LST and ''moderate'' to ''very strong'' at 1500 LST. Geographical consistency exists within each season over the decades, with a critical ''very strong'' heat stress period during March-May. Additionally, there has been an increasing spatial expansion of areas experiencing higher heat stress levels across the country. Latitudinally, stable patterns exist across decades at 0600 LST for each season. Seasons show distinct UTCI values, and at 1500 LST, more variability and category transitions occur along latitudes. Furthermore, the results indicate significant positive trends and occasional non-significant negative trends over the 40-year period. Notably, during 0600 LST, the Guinea and Sahel regions exhibit relatively higher positive trends than the Sudan region in all seasons, whereas at 1500 LST, high positive trends are prominent in DJF and MAM seasons, indicating increased heat stress during peak seasons. These positive deviations in UTCI are associated with adverse effects on human health, including increased mortality rates.

We have attempted to investigate the spatiotemporal patterns and fluctuations in summer thermal heat stress/discomfort over the Indian region-based universal thermal climate index (UTCI) in this study. We have calculated UTCI using hourly ERA5 data of 10 m wind speed, 2 m air temperature, 2 m dew point temperature, and solar radiation for the period 1990–2020. To determine the effect of radiation fluxes and soil moisture on temperature and UTCI, we have used ERA5 data on cloud fraction (CF), surface heat fluxes (SLHF and SSHF), and soil moisture (SM) for the study period. Maximum heating and discomfort have been reported in May for most of the regions. Except for the west region, the progress of the monsoon provides some relief in June. Maximum discomfort is observed around 08–09Z. We have observed over 50% of India experiencing a decreasing trend in UTCI in different summer months despite over 50% of India experiencing an increasing trend in temperature. This is due to the influence of factors such as solar radiation, cloudiness, wind speed, soil moisture, etc., on UTCI. The UTCI in summer months demonstrates spatial heterogeneity. UTCI increases significantly in the west region in April and the east region in June. In April and May, some portions of the South-Central region, particularly Maharashtra, exhibit an increasing trend in UTCI. The majority of the North-Central region has a noticeable decreasing tendency in UTCI in all the summer months. We have not found any significant trend in the frequency of days with ‘very high heat stress’ or higher discomfort. Except in the eastern region, there is no noticeable trend in the frequency of discomfort hours with UTCI in the ranges 38 < UTCI < 46°C and UTCI > 46°C. The Eastern region exhibits an increasing trend in the frequency of discomfort hours with UTCI in the range of 38 < UTCI < 46°C in April. The Eastern region has a rising trend in the frequency of discomfort hours, with UTCI in the range of 38 < UTCI < 46°C in April. [ABSTRACT FROM AUTHOR]

Progressing climate change is often reflected in changing biometeorological conditions. The Sudetes Mountains, located in the Polish–Czech border area, are concerned by this phenomenon. The goal of this paper is to evaluate the influence of atmospheric circulation on multiannual changes in biothermal conditions using the UTCI index. In the analysis, data for 1991–2020, from both Polish and Czech meteorological stations, was considered, while the circulation factor was evaluated using the Lityński classification. The research indicated a positive tendency of UTCI values for the majority of circulation types, which consequently contributed to a decrease in the frequency of cold stress categories. In the summits, a decline in the number of days with extreme cold stress was the most characteristic feature, especially under anticyclonic and northern circulation. Tendencies of heat stress occurrence were in most cases statistically insignificant, except for cyclonic and transitional circulation.

Significance: An article in the July/August 2022 issue (Havenga et al., S Afr J Sci. 2022;118(7/8), Art. #13118) argued that changing the date of the Comrades Marathon from May to August would result in increased heat stress for participants. Heat stress was estimated using the Universal Thermal Climate Index (UTCI), which is designed to represent a person walking, not running. In this Commentary, I argue that using the UTCI may lead to an underestimation of heat stress for the Comrades Marathon, and that the conclusion that August has worse heat stress than May depends on the assumptions in the estimation of heat stress. [ABSTRACT FROM AUTHOR]

The large number of thermal indices introduced in the literature poses a challenge to identify the appropriate one for a given application. The aim of this study was to examine the effectiveness of widely used indices in quantifying the thermal environment for operational weather applications within a Mediterranean climate. Eight indices (six simple and two thermo-physiological) were considered, i.e., apparent temperature, heat index, humidex, net effective temperature (NET), physiologically equivalent temperature (PET), universal thermal climate index (UTCI), wet-bulb globe temperature, and wind chill temperature. They were estimated using hourly meteorological data between 2010 and 2021, recorded in 15 stations from the Automatic Weather Station Network of the National Observatory of Athens in the Athens metropolitan area, Greece. The statistical analysis focused on examining indices' sensitivity to variations of the thermal environment. NET, PET, and UTCI were evaluated as suitable for operational use, assessing both cool and warm environments, and extending their estimations to the entire range of their assessment scales. NET and PET often tended to classify thermal perception in the negative categories of their scales, with 63% of NET and 56% of PET estimations falling within the range of cool/slightly cool to very cold. UTCI estimations in the negative categories accounted for 25.8% (p < 0.001), while most estimations were classified in the neutral category (53.1%). The common occasions of extreme warm conditions in terms of both air temperature (Tair) and NET was 77.7%, Tair and UTCI 64.4%, and Tair and PET 33.6% (p < 0.001). According to the indices considered and the method followed, NET and UTCI satisfied sufficiently the requirements for operational use in the climate conditions of the Mediterranean climate. [ABSTRACT FROM AUTHOR]

Heatwaves have caused significant damage to human health, infrastructure, and economies in recent decades, and the occurrences of heatwaves are becoming more frequent and severe across the globe under climate change. The previous studies on heatwaves have primarily focused on air temperature, neglecting other variables like wind speed, relative humidity, and radiation, which could lead to a serious underestimation of the adverse effects of heatwaves. To address this issue, this study proposed to the use of more sophisticated thermal indices, such as universal thermal climate index (UTCI) and apparent temperature (AT), to define heatwaves and carry out a comprehensive heatwave assessment over mainland southeast Asia (MSEA) from 1961 to 2020. The traditional temperature-based method was also compared. The results of the study demonstrate that the annual maximum temperature in heatwave days (HWA) and the annual average temperature in heatwave days (HWM) are significantly underestimated if only air temperature is considered. However, UTCI and AT tend to predict a lower frequency of yearly heatwave occurrences and shorter durations. Trend analysis indicates a general increase in heatwave occurrences across MSEA under all thermal indices in the past six decades, particularly in the last 30 years. This study's approach and findings provide a holistic view of heatwave characteristics based on thermal indices and highlight the risk of intensified heat stress during heatwaves in MSEA. [ABSTRACT FROM AUTHOR]

This work investigates the possible future changes and impacts in spatiotemporal variation and regional features of multivariate compound heatwaves (CHWs) in China using the latest Universal Thermal Climate Index from the Coupled Model Intercomparison Project Phase 6 simulations (CMIP6). Results indicate both strong CHWs and extremely threatening CHWs in China are projected to increase substantially in both frequency and spatial extent under different future climate scenarios while with discernible regional disparities. The more severe global warming is, and the greater the extremity of the heatwave events is, the faster the increase in CHWs is. These findings are derived from the CMIP6 projections calibrated using the robust empirical quantiles method. Climate change causes more areas and people to be exposed to CHWs. Notably, the population exposure to dangerous CHWs will increase significantly in northwest China and will appear in northeast China after the mid‐21st century under the high emission scenario. Plain Language Summary: Extreme multivariate compound heatwaves (CHWs) may have devastating impacts on human health and have attracted significant societal attention. We explored the possible future changes in dangerous multivariate CHWs in China based on the latest Universal Thermal Climate Index (UTCI) from the Coupled Model Intercomparison Project Phase 6 simulations (CMIP6) project. Results show that the CMIP6 UTCI in China has a warm bias compared to the observations. A nonparametric quantile mapping using a robust empirical quantiles method is employed which can effectively correct this bias and is used to constrain future CMIP6 projections to reduce uncertainties. Two categories of dangerous CHWs are investigated in the current work, that is, strong compound heatwaves and extremely threatening CHWs. Results indicate an expected acceleration in the rate of CHWs and population exposure after the mid‐21st century, primarily driven by climate changes. Moreover, the rate of acceleration is found to be more pronounced for CHWs of higher extremities and in the context of the increased severity of global warming. Additionally, population exposure to extremely threatening CHWs will increase significantly not only in southeastern China but also in northwestern and northeastern regions. Our study highlights the critical importance of mitigating climate change to minimize the threat posed by dangerous CHWs to human populations. Key Points: A nonparametric quantile mapping method can effectively correct the warm bias in the latest Coupled Model Intercomparison Project Phase 6 simulations Universal Thermal Climate Index in ChinaThe increasing rate of compound heatwaves (CHWs) in China will accelerate with the increase in the event extremity and severity of warmingPopulation exposure to CHWs will increase significantly in northwest and northeast China in a warmer world [ABSTRACT FROM AUTHOR]

Millions of people travel to European beaches making beach tourism the largest tourism sector. Understanding how person’s thermal comfort changes with projected climate change, which is paramount in deciding where and when to visit, can help the tourism sector mitigate risk and identify opportunities. Sustainable adaptation strategies for coastal tourism can be developed for different regional changes. This work calculates the Universal Thermal Comfort Index (UTCI), a comprehensive assessment of the human physiological response to the thermal environment, from an ensemble of regional climate models participating in EURO-CORDEX. Under Representative Concentration Pathways (RCP) 8.5, the ensemble’s projections of the UTCI in the near- and far-future, compared to a historical reference period, show a robust and statistically significant increase across the entire EURO-CORDEX domain. Four popular beach regions in Germany, Italy, France, and Spain show the beach season can be extended - starting earlier and ending later each year. Across the Mediterranean, July and August exhibit, on average, 4 more days of ‘very strong’ heat stress and 1 day of ‘extreme’ heat stress at the end of the century. In accordance with FAIR data science principles, the UTCI calculation is available in the xclim open-source python library.

Adopting a multiscale approach is crucial for optimizing urban and building performance, prompting inquiries about the link between a technology’s local efficiency (building scale) and its broader impact (city-wide). To investigate this correlation and devise effective strategies for enhancing building and city energy performance, we experimentally examined a commercial nano-ceramic Thermal Barrier Coating (TBC) on a small-scale building and assessed numerically its influence on mitigating Urban Heat Islands (UHIs) at a city scale, translated in our case by the use of the thermal comfort index: the Universal Thermal Climate Index (UTCI). Our results reveal that the coating significantly curbs heat transfer locally, reducing surface temperatures by over 50 ∘C compared to traditional roofs and attenuating more than 70% of heat flux, potentially alleviating air conditioning demands and associated urban heat effects. However, implementing such coatings across a city does not notably advance overall efficiency and might trigger minor overheating on thermal perception. Hence, while nano-ceramic coatings indirectly aid UHI mitigation, they are not a standalone fix; instead, an integrated strategy involving efficient coatings, sustainable urban planning, and increased vegetation emerges as the optimal path toward creating enduringly sustainable, pleasant, and efficient urban environments to counter urban heat challenges effectively.

The health of urban populations is increasingly at risk due to the amplification and chronification of urban heat stress by climate change. This is particularly true for urban environments in humid tropical climates, including many cities in Southeast Asia. It is also in these locations where increasing climatic risks may be exacerbated by urban growth, underscoring the need to develop effective mitigation strategies for strengthening urban resilience and supporting climate change adaptation. Conservation and widespread implementation of green infrastructure (GI) are regarded as one means to counter heat as a public health threat. However, for lower-income countries across Southeast Asia, such as Vietnam, knowledge gaps remain with respect to the effectiveness of greening interventions for heat mitigation. To address this gap, in the context of urban expansion in the humid tropical city of Huế, Vietnam, diurnal cooling potential and regulation of outdoor thermal comfort (OTC) within a wide, shallow street canyon were systematically assessed for selected elements of GI along a quantitative and qualitative dimension using ENVI-met. Tree-based interventions were found to be most effective, potentially decreasing UTCI by −1.9 K at the domain level. Although lower in magnitude, green verges and green facades were also found to contribute to OTC, with green verges decreasing UTCI by up to −1.7 K and green facades by up to −1.4 K locally. Potential synergistic cooling impacts were identified through a combination of GI elements. However, no scenario was found to decrease heat stress to zero or moderate levels. Substantially reducing heat stress may thus require further measures and a closer consideration of local morphological characteristics.

Open data set: https://doi.org/10.5281/zenodo.8348335

Urban climate and its impact on the thermal comfort of residents are significant aspects in urban planning and the design of housing estates. The aim of this article is to investigate the temperature perception among residents in a contemporary residential area in Lublin during the hottest day, utilising an advanced computer simulation tool – the ENVI-met programme. A modern, densely built housing estate with no significant greenery was selected as a case study. General meteorological and spatial data were used for calibrating the housing estate model within the software. The housing estate model within the programme was calibrated using publicly available meteorological and spatial data, and computer simulations were conducted for Lublin's hottest day on 22 July 2022. Based on these simulations, the Universal Thermal Climate Index (UTCI) was calculated. The research results indicate that people experience moderate thermal stress in unshaded areas only at 4:00 pm, while in sunny locations, they experience strong to very strong heat stress throughout the day. This article underscores the importance of computer simulations in analysing the urban microclimate and provides insights into tools that can be used in urban planning and housing estate design processes, with the aim of creating more comfortable and environmentally friendly urban environments.

Abstract This work investigates the possible future changes and impacts in spatiotemporal variation and regional features of multivariate compound heatwaves (CHWs) in China using the latest Universal Thermal Climate Index from the Coupled Model Intercomparison Project Phase 6 simulations (CMIP6). Results indicate both strong CHWs and extremely threatening CHWs in China are projected to increase substantially in both frequency and spatial extent under different future climate scenarios while with discernible regional disparities. The more severe global warming is, and the greater the extremity of the heatwave events is, the faster the increase in CHWs is. These findings are derived from the CMIP6 projections calibrated using the robust empirical quantiles method. Climate change causes more areas and people to be exposed to CHWs. Notably, the population exposure to dangerous CHWs will increase significantly in northwest China and will appear in northeast China after the mid‐21st century under the high emission scenario.

Previous studies have shown that tree arrangement provides effective regulation of the outdoor thermal environment and combats the urban heat island (UHI) effect. To further explore semi-outdoor thermal environment improvement using tree arrangement, we selected two common arbor species from Guangdong Province, namely, Lagerstroemia speciosa and Bombax ceiba. We discuss the influence of courtyard tree arrangements on the thermal environment of semi-outdoor spaces (courtyards and overhead spaces) of a teaching building in a hot-humid area. The ENVI-met model was used and verified with field measurements; the universal thermal climate index (UTCI) was used as an index to evaluate the thermal environment of semi-outdoor spaces. We found that (1) adjusting the distance between trees and buildings reduced the UTCI values by 0.4 (overhead spaces) and 0.8 ℃ (courtyards); and (2) when the distance between the arbor and the building is fixed, the UTCI values of arranging Lagerstroemia speciosa can be reduced by up to 0.5 (overhead spaces) and 1.0 ℃ (courtyards) compared to that of Bombax ceiba; this study provides practical suggestions for the layout of trees in semi-outdoor spaces of teaching buildings in the hot-humid areas of China. [ABSTRACT FROM AUTHOR]

To assess thermal comfort of residences, several different factors as meteorological, physiological, and socio-cultural, should be considered. The integrated effect of these variables on thermal stress can be obtained and evaluated using thermal comfort indices. Thermal comfort as a bio- meteorological index is of special importance. The purpose of this research is to analyze the seasonality and trend of heat stress in Iran in the period from 1981 to 2020. In this research, the Universal Thermal Climate Index (UTCI) index as a common thermal index was evaluated for outdoor thermal comfort, using ERA5 dataset. ERA5 is the fifth generation ECMWF reanalysis data for the global climate and weather for the past 4 to 7 decades. The ERA5 provides hourly estimates for a large number of atmospheric, ocean-wave, and land-surface quantities. An uncertainty estimate is evaluated by an underlying 10-member ensemble at three-hour intervals. Such uncertainty estimates are closely related to the information content of the available observing system which has improved considerably over time. They also indicate flow-dependent sensitive areas (Hersbach et al., 2020). Also, root mean square error (RMSE), Percent bias (PBIAS), Nash- Sutcliffe model efficiency coefficient (NSE), and Root Mean Standard Deviation Ratio (RSR) metrics were used to evaluate the quality of ERA5 dataset. The seasonal variability of the UTCI index shows that this index has significant regional heterogeneity in Iran. The increase in UTCI from the north to the south of Iran leads to an increase in thermal stress. The spatial distribution of areas that do not have thermal stress during the hot period of the year are mainly consistent with the altitudes. During the cold seasons of the year, areas with elevations of more than 3,000 meters in Iran have moderate cold stress. The investigation of the trend of thermal stress during the last four decades, which was analyzed with the modified Mann-Kendall test, shows that the UTCI in Iran has a dominant increasing trend. The UTCI index shows an increasing trend in the spring and autumn seasons by 100%, and in the winter and summer seasons at 99.83 and 99.75% of the country, respectively. The maximum significant increasing trend of the index at the level of 0.05 was achieved in the spring. In the same way, the highest value of Sen's slope estimator test of the area-averaged trend is also seen with the value of 0.52 °C in this season in the study period. The results of this study for climatology and the trend of the UTCI index in Iran show that: 1- There is a close relationship between heat and cold stresses in Iran and topography, but this relationship is not a linear; 2- Along with global warming, the UTCI index in Iran during the years 1981-2020 has shown an increasing trend; 3- In general, areas with UTCI cold stress in the country are decreasing and areas with heat stress are increasing; 4- One of the key findings in this study is the significant increase in trend of the UTCI index in the spring season. [ABSTRACT FROM AUTHOR]

The study objective was to characterise biometeorological conditions during the long May weekend (1–3 May) in Poland in the period 1966–2020 and determine baric conditions causing their variability. The conducted research employed data such as air temperature, relative humidity, wind speed, and total cloudiness. The aforementioned data were collected at 12:00 UTC. In the first year of the conducted study, the Universal Thermal Climate Index (UTCI) was calculated for the period of 1–3 May in the years 1966–2020. Next, circulation conditions were analysed in the designated groups based on daily sea level atmospheric pressure values and isobaric surface height of 500 hPa. This study evidenced the occurrence of variable biometeorological conditions during the long May weekend in Poland. The lowest index values were recorded at the coast of the Baltic Sea and in Northeast Poland, and the highest in the southern and western regions. On the analysed days of May in the years 1966–2020, days classified as days with no thermal stress were recorded the most frequently, followed by days with cold stress, and days with warm stress that occurred sporadically. People planning tourist activity on the analysed days should be prepared for diverse biometeorological conditions, from those causing cold stress to those causing heat stress. [ABSTRACT FROM AUTHOR]

Adopting a multiscale approach is crucial for optimizing urban and building performance, prompting inquiries about the link between a technology's local efficiency (building scale) and its broader impact (city-wide). To investigate this correlation and devise effective strategies for enhancing building and city energy performance, we experimentally examined a commercial nano-ceramic Thermal Barrier Coating (TBC) on a small-scale building and assessed numerically its influence on mitigating Urban Heat Islands (UHIs) at a city scale, translated in our case by the use of the thermal comfort index: the Universal Thermal Climate Index (UTCI). Our results reveal that the coating significantly curbs heat transfer locally, reducing surface temperatures by over 50 ∘ C compared to traditional roofs and attenuating more than 70% of heat flux, potentially alleviating air conditioning demands and associated urban heat effects. However, implementing such coatings across a city does not notably advance overall efficiency and might trigger minor overheating on thermal perception. Hence, while nano-ceramic coatings indirectly aid UHI mitigation, they are not a standalone fix; instead, an integrated strategy involving efficient coatings, sustainable urban planning, and increased vegetation emerges as the optimal path toward creating enduringly sustainable, pleasant, and efficient urban environments to counter urban heat challenges effectively. [ABSTRACT FROM AUTHOR]

The present study concerns the determination of the characteristics of bioclimatic conditions, as well as the synoptic situations related to the occurrence of thermal stress conditions, in Poland. The study was based on daily data obtained from the Institute of Meteorology and Water Management – National Research Institute from the period 1966–2020 for 37 synoptic stations in Poland. Based on the obtained data, values of the Universal Thermal Climate Index (UTCI) were calculated. The occurrence of heat stress increases from the north to the south, corresponding with the variability of influx of solar radiation, and is modified by factors at a smaller spatial scale. The results of this paper evidently point to the cooling effect of the waters of the Baltic Sea. In circulation conditions favouring strong and very strong heat stress, e.g. in two of the designated circulation types (T1 and T2), the occurrence of an expansive high-pressure ridge in the Atlantic-European area is typical, stretching from the region of the Azores High towards the north-east, with a secondary high developed within its boundaries. In the third of the designated circulation types (T3), the high-pressure area extends from the Azores eastwards, reaching the Black Sea. Each of the three circulation patterns associated with the unfavourable biometeorological conditions of very strong and extreme cold stress in Poland is characterised by strong pressure centres formed in the Euroatlantic region, triggering the airflow from the northern (T4) or eastern (T5, T6) sector.

The article analyzes heat waves in Sarajevo in the period 1901-2018. We presented the trends in the number of heat waves, their length, the highest air temperatures during heat waves and the cumulative highest temperatures during heat waves. We also discussed the trends of the universal thermal climate index for Sarajevo in the period 1961--2018, which show the burdensome thermal effect on humans in a more integral way. In Sarajevo we observe an increase in the number of heat waves, the number of days in heat waves and the cumulative maximum temperatures in heat waves. After 1961, the burdensome thermal effect in the summer months also increases, which also indicates a positive trend in the value of the universal thermal climate index. [ABSTRACT FROM AUTHOR]

The set of meteorological data from the Jagiellonian University station in Kraków is one of the longest‐recorded in central Europe. Measurement records date back to 1826. Based on the average monthly values of air temperature, total cloudiness, water vapour pressure and wind speed at 1200 UTC, the UTCI values were calculated and the occurrence of cold stress (UTCI < −13°C) and heat stress (UTCI > 32°C) was estimated. The variability of the applied measures of thermal stress conditions was studied both annually and in individual seasons (MAM, JJA, SON, DJF). Statistically significant changes in the studied characteristics of the bioclimate were found. Average annual UTCI values increased at the rate of 0.27°C/10 years. In individual seasons, the trend of UTCI changes ranged from 0.10°C/10 years in summer to 0.43°C/10 years in winter. The number of days with cold stress decreased by 1.8 days/10 years and the number of days with heat stress significantly increased (0.5 days/10 years). Two subperiods with different trends of changes were determined. The first covers the years 1826–1940, and the second, 1941–2021. The former indicates a negative UTCI trend of −0.17°C/10 years, and the latter, an increasing trend of 1.09°C/10 years. The last eight decades have brought a decrease in cold days of 6.5/10 years and an increase in heat days of 2.6/10 years. [ABSTRACT FROM AUTHOR]

W analizie bilansu cieplnego człowieka największym problemem jest określenie ilości promieniowania pochłoniętego przez człowieka. Dlatego też w badaniach komfortu cieplnego stosuje się uproszczenia i jako miarę termicznego wymiaru pola promieniowania wokół człowieka stosuje się koncepcję średniej temperatury promieniowania - Mrt (Mean radiant temperature), która traktuje łącznie wszystkie strumienie promieniowania długo-i krótkofalowego, na które eksponowane jest ludzkie ciało. Na terenach zurbanizowanych do określenia wartości Mrt sugeruje się prowadzenie bezpośrednich pomiarów tego parametru. Najczęściej wykorzystuje się do tego termometr kulisty - z uwagi na prostotę jego konstrukcji, niski koszt oraz łatwość użytkowania. Celem pracy jest zweryfikowanie przydatności termometrów kulistych do pomiarów Mrt, określenie zależności ich wskazań od wartości parametrów meteorologicznych oraz ustalenie wpływ sposobu oszacowania Mrt na wartości wskaźnika UTCI (Universal Thermal Climate Index). Do wyznaczenia Mrt użyto trzech termometrów kulistych: jeden standardowy 15-centymetrowy (SGT) oraz dwa 4-centymetrowe akrylowe (AGT) własnej konstrukcji. Badania wykonano na terenach otwartych oraz w cieniu drzew. Typ zastosowanego instrumentu pomiarowego istotnie wpływa na wielkość Mrt w warunkach silnego usłonecznienia - najwyższe wartości Mrt uzyskano za pomocą SGT, a najniższe przy pomocy szarego AGT. W cieniu wszystkie typy przyrządów wskazywały zbliżone do siebie wartości. Błąd oszacowania UTCI w efekcie niepewności wyznaczonych wartości Mrt za pomocą różnych termometrów kulistych, odpowiada jednej kategorii stresu termicznego w warunkach radiacyjnych, natomiast w cieniu jest zaniedbywalny. [ABSTRACT FROM AUTHOR]

W pracy scharakteryzowano obciążenia cieplne człowieka w trzech najgorętszych miesiącach, które wystąpiły w Krakowie na początku XXI w., a mianowicie w lipcu 2006 r., sierpniu 2015 r. i czerwcu 2019 r. Podstawę badań stanowiły wartości wskaźnika UTCI obliczone na bazie czterech elementów meteorologicznych z trzech terminów obserwacji w ciągu doby (6, 12 i 18 UTC). Jako okres referencyjny przyjęto ostatnie trzydziestolecie 1991-2020. W opracowaniu wykorzystano także kalendarz typów cyrkulacji i mas powietrznych nad południową Polską (Niedźwiedź, 1981, 2023). Na postawie średnich wartości charakterystyk termicznych, jak i wskaźnika UTCI, wykazano, że warunki odczuwalne w 3 niezwykle ciepłych miesiącach były podobne. Ogólnie dni ze stresem ciepła (o 12 UTC) było rekordowo dużo: od 70% w sierpniu 2015 r. do 84% w czerwcu 2019 r. Przebieg obciążeń z dnia na dzień był nieco odmienny. Potwierdziło się, zgodnie z dotychczasową wiedzą, że o nasileniu gorąca zadecydowały zarówno charakter cyrkulacji, jak i kierunek adwekcji i typ masy powietrznej. Podczas niezwykle ciepłych miesięcy w dniach z najsilniejszym stresem ciepła przeważała cyrkulacja antycyklonalna z sektora południowego (Sa i SWa), sprowadzająca gorące masy powietrza zwrotnikowego. [ABSTRACT FROM AUTHOR]

Long- and short-term biometeorological conditions in the Republic of Serbia were analyzed using official meteorological data from numerous weather stations located across the country. Selected biometeorological indices HUMIDEX, Physiologically Equivalent Temperature (PET), and Universal Thermal Climate Index (UTCI) are calculated based on air temperature, relative humidity, wind speed, and cloudiness data from the meteorological stations on annual and summer level as well as during selected heat wave periods during 2000–2020. Application of different biometeorological indices provides similar but somewhat different results. For example, average annual HUMIDEX and UTCI values indicate no thermal stress and no discomfort at all stations, while PET indicates the occurrence of slight to moderate cold stress at all stations. Average summer PET and UTCI indicate the occurrence of slight to moderate heat stress throughout the country, while HUMIDEX indicates no discomfort. Trends of biometeorological indices on annual and summer level show a general increase throughout the country. Furthermore, heat wave analysis indicated that the most populated cities of Serbia are under dangerous and extreme heat stress during these extreme temperature events, which can influence human health and well-being. The obtained biometeorological information can be used for the preparation of climate adaptation strategies that consider the human biometeorological conditions, with a special focus on developing climate-sensitive and comfortable cities. [ABSTRACT FROM AUTHOR]

The study aims to present reliable information about thermal conditions and their impacts on visitors to ski travel destinations. Mountain tourism areas are specific since high altitudes affect the ambient weather conditions which can affect different types of human activities. In this paper, the thermal comfort and its changes in Kopaonik Mountain, the most popular ski resort in Serbia over the last 30 years, have been evaluated. Information about thermal comfort is presented by using the Universal Thermal Climate Index (UTCI), physiologically equivalent temperature (PET), and modified physiologically equivalent temperature (mPET) in 3-h resolution for the period 1991–2020. The results indicate prevailing cold stress all year round. Days with moderate, strong, and very strong heat stress were not recorded. Strong and extreme cold stress prevailed during winter, while slight and moderate cold stress prevailed during summer. Transitional seasons were very cold, but autumn was more comfortable than spring. The occurrence of days with neutral and slightly warm/cool conditions is concentrated in the summer months. However, summer is not used enough for tourism because the choice of tourists to stay at Kopaonik is not primarily based on favorable bioclimatic conditions, but on resources for winter tourism. With global warming, the annual number of thermally favorable days has been increasing, while the number of days with extreme and strong cold stress is decreasing. Continuing this trend can significantly influence tourism in the future, and therefore, new strategies in ski resorts will be required to adapt to the changing climate. [ABSTRACT FROM AUTHOR]

With the aim of guaranteeing the interests and health of tourists, this study comprehensively evaluates the suitability of the environment in different cities in China for tourism by considering the impacts of climate, vegetation and environmental factors on health. The Universal Thermal Climate Index (UTCI), total precipitation (PREC), Vegetation Leaf Area Index (LAI), concentration of particulate matter with a diameter of less than 2.5 μm (PM2.5), and the downward UV radiation at the surface (UVB) are used as indices. In addition, the Delphi–AHP–TOPSIS algorithm is introduced and is used for the comprehensive evaluation of the environmental suitability of 684 cities in China for tourism in 2019. It is found that Chinese cities vary greatly in terms of the suitability of their environments for tourism. Among the factors that affect the environmental suitability, the LAI is important, with an increase in the LAI generally being advantageous. In contrast, an increase in the PM2.5 concentration is a key factor that limits the environmental suitability of an area. Thus, urban landscaping and control of the atmospheric quality are essential and effective ways of improving the suitability of the environment of cities in China for tourists.

The primary objective of the study was the determination of the spatial and multiannual variability of occurrence of days with very strong and extreme cold stress in Poland according to the Universal Thermal Climate Index (UTCI), as well as determination of baric conditions favouring their occurrence. The study was based on data from the years 1966/67 to 2018/19 from the Institute of Meteorology and Water Management – National Research Institute and National Centre for Environmental Prediction/National Centre for Atmospheric Research (NCEP/NCAR). The research showed a statistically significant decrease in the number of days with very strong and extreme cold stress on half of the analysed stations, and a slight tendency or no changes on the remaining stations. The occurrence of days with extreme cold stress in Poland, as revealed by the analysis was primarily related to the presence of high-pressure systems blocking zonal circulation. The study resulted in the designation of three circulation types, i.e. two types related to anticyclonic systems and one cyclonic type.

The green transformation of the built environment is aimed at improving sustainability and can be supported by digitalization, which has become a significant tool to support the supply, integration, and management of information throughout the construction life cycle. In addition, climate change highly affects human comfort in the built environment and different strategies should be evaluated for adapting cities. This paper developed a digital workflow by integrating existing tools (i.e., Grasshopper, Ladybug, Honeybee, and Dragonfly) to evaluate how different green infrastructure strategies affected the thermal comfort by reducing the UTCI. The workflow was applied to a typical historical urban context (Catania, South of Italy), consisting of a square surrounded by three-floor buildings. Three basic scenarios were created that depended on the pavement material used in the built environment: a black stone pavement (reference material from Mount Etna), a permeable pavement, and grass. These three scenarios were combined with different green infrastructure strategies: tree pattern on the square, green walls and green roofs on the surrounding buildings, and the integrations of all these above-mentioned strategies. The results demonstrated that the integration of different green strategies (a grass square instead of pavement, with trees, and green walls and green roofs) increased the thermal comfort by reducing the UTCI by more than 8 °C compared to the existing urban context (black stone pavement and building envelope). However, this temperature reduction was highly affected by the location of the human body into the urban context and by the evaporation rates from vegetation. The workflow developed will be useful for designers to evaluate the effectiveness of different green strategies during the early-design stage in mitigating and adapting cities to climate change. [ABSTRACT FROM AUTHOR]

Regarding the predisposition of individuals to change when confronted with future climate scenarios, it is necessary to understand the perception of the groups under analysis and how to engage with society to collectively act toward climate change mitigation. A question remains to be answered: how to ensure that people engage, participate, and gain awareness of the undergoing problem that urban climate change poses for the future of cities' management? This research intends to contribute to solving this question by raising another question: "How willing are residents of the Alvalade neighborhood (Lisbon) to change their behavior and way of life when faced with climate change scenarios?" We present a methodology using microclimatic modeling with ENVI-met and questionnaires for the resident community. The present and future local climate scenarios (representing a present hot day versus the extreme IPCC RCP 8.5 scenario) were presented to a set of residents. These figures show the projected UTCI (Universal Thermal Climate Index) in a dramatic but accurate aggravated way. The inquiries allowed us to conclude that people are more aware of local climate change and health risks from extremely hot summer weather, but they continue to resist adopting behavior change for adaptation, although most of them declared this could be important to tackle climate change. The second conclusion is that people think that local authorities should be more active than themselves and will have greater responsibility for climate change adaptation and interventions. In times of climate crisis, the participation of the resident community can be an important help in decision making and finding measures to mitigate adverse climate effects in urban environments. [ABSTRACT FROM AUTHOR]

The high-density development of urban centers has worsened outdoor thermal comfort in many cities. In this study, ENVI-met was used to simulate thermal comfort, and the universal thermal climate index (UTCI) and eight urban morphological indicators were calculated at 348 sampling points in the urban center. The correlation results are shown as follows: (1) Thermal comfort is significantly and positively correlated with impervious surface, green area ratio, and sky openness, showing a strong negative correlation with building density, floor area ratio, and shadow hours. (2) The UTCI value decreases by 0.998 °C for every 1 h increase in shadow hours, increases by 0.746 °C for every 10% increase in sky view factor, decreases by 0.462 °C when the building density increases by 10%, and decreases by 0.596 °C for every 10% increase in the impervious area ratio. (3) The sampling points with better thermal comfort have similar spatial characteristics such as higher building density, higher volume ratio, smaller green area ratio, longer shadow hours, and smaller sky openness. (4) In the planning and design of urban centers, increasing shade can improve the shadow hours in the environment. Specifically, large open sites should be avoided. [ABSTRACT FROM AUTHOR]

Due to climate change crisis, the risk of occupational heat stress for agricultural workers has recently increased. The temporal and spatial biometeorological conditions in different climatic regions of Slovenia during summer were analyzed using the Universal Thermal Climate Index (UTCI), and additionally the water loss index (SW) and the accepted level of physical activity (MHR). Term values of air temperature, relative air humidity, wind speed at 10 m and cloud cover at 14:00 CEST were used as input for the BioKlima 2.6 software package and were retrieved from the Slovenian Environment Agency for the summer months in the period 2000–2021. The rise in the average UTCI values was shown to be positive and statistically significant for summer (0.7 °C/decade) as well as for all three months, the highest being for June (0.9 °C/decade). The percentage of summer days during 2000–2021 that were under strong or very strong heat stress varied widely by location, ranging from one-third to more than one-half. Average monthly UTCI values at 14:00 CEST were the highest in July, reaching 30 °C in a submediterranean climate, Črnomelj is the only station with this average higher than 32 °C. Daily highest UTCI value was 47 °C (Črnomelj). It was shown that conditions in the middle of a hot summer day are not suitable for moderate or severe agricultural workloads. [ABSTRACT FROM AUTHOR]

Extreme heat is a current and future issue on urban areas, with negative impacts on health and quality of life (increasing morbidity and mortality rates). This paper analyses day (12:00–15:00 h) and nighttime (00:00–03:00 h) thermo-physiological comfort (TC) conditions by Local Climate Zones (LCZ) in Lisbon during a particular Local Weather Type (LWT), very hot summer days. For this, 13 different microscale sample areas were chosen covering urban and non-urban land cover classes (LCZs 1–3, 4–6, 8, 9, A and B). Universal Thermal Climate Index (UTCI) and Mean Radiant Temperature (MRT) were modeled on SkyHelios software for 163 days between 2008 and 2014. Results show that during the day all urban LCZ samples depict the same average TC conditions (average UTCI of 34°C—strong heat stress) and densely wooded areas are 2°C cooler (average UTCI of 32°C—moderate heat stress). However, compact areas (LCZs 1–3) with low sky view factor and some vegetation (street trees) display lower percentages of area with higher thermo-physiological discomfort (TD) levels (83% with strong heat stress against 98% in LCZs 8 and 9 and 100% in LCZs 4–6). When considering the hottest days (air temperatures equal or above 35°C—75th percentile), the moderate heat stress class disappears in all samples and the very strong heat stress class appears only on urban areas, occupying between 12% and 16% on LCZs 1–3, 10%–22% on LCZs 4–6, 16%–22% on LCZs 8 and 9 on LCZ 9. During the nighttime period all samples show no thermal stress, favoring nocturnal physiological recovery. TC conditions in Lisbon are strongly influenced by solar radiation and wind, which explains the need to increase the shading area, preferably by trees, and to promote and preserve ventilation paths.

The main goal of this research is to examine thermal comfort in the central area of Belgrade (Serbia), over a period of 30 years (1991-2020). The Universal Thermal Climate Index (UTCI) was used as a measure for evaluating outdoor thermal comfort (OTC). The obtained results were considered separately for each season, as well as at the annual level. The analysis was carried out on the basis of an extensive database, which included hourly values (7h, 14h, 21h CET) of meteorological parameters, as well as their average daily, minimum, and maximum values. The obtained values of UTCIs show a positive growth trend during all four seasons. A significant increase in the annual values of UTCIs was also recorded. Four of five years with the highest average UTCIs were recorded in the last decade of the survey, more precisely in the period 2015-2020. The years that stand out for the frequency of record spring, autumn and winter UTCIs values are 2017, 2018, 2019 and 2020. On an annual level, minimum UTCI value has rising trend of 0.099°C/year, while at maximum UTCI value, that trend is 0.081°C/year. [ABSTRACT FROM AUTHOR]