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Ships' logbooks have been preserved in archives of different European countries. This paper reviews how their records provide reliable information relevant to meteorology and climatology, extending the observational record back to at least the early 18th century. This allows describing weather during historical events, improving the knowledge on hurricanes or unveiling multidecadal variability previously unsuspected, such as the steady enhancement of the Australian monsoon, the high variability of the atmospheric circulation over the Euro‐Atlantic region during the Late Maunder Minimum or the relationship between the Western North Pacific Summer Monsoon and the El Niño—Southern Oscillation. Observations from ships can feed long‐term reanalysis projects and contribute to reduce their uncertainties over the oceans. The extended record of observations also aids the search of analogues before the human fingerprint, thus improving the detection and attribution of climate change. The integration with paleoclimate proxies is a complex task that requires merging heterogeneous records with a wide range of time resolutions, spatial density, and responses to the climate system. However, recent international efforts open the field to new opportunities. Summing up, logbooks are a consistent, but underexploited, source of relevant climatic data that will widen our knowledge of the past climate. This in turn provides a way to better understand present climatic variations and predict future changes., This research was funded by the Spanish Ministerio de Economía y Competitividad through the projects CGL2013‐44530‐P, CGL2014‐51721‐REDT, CGL2015‐69699‐R, and CGL2015‐72164‐EXP/AEI.

The purpose of this study is the characterization of the synoptic circulation patterns leading to extremely warm periods (EWPs) over the Kurdistan province of Iran. Daily maximum temperature data from 27 meteorological stations were used for the period 1962–2012. Data were interpolated to a 6 × 6 km grid using the geospatial Kriging method. EWPs were defined as a period of at least 6 consecutive days with maximum temperature above the local daily‐based 95th percentile of the 1971–2000 period, with additional criteria for spatial extension. The identified EWPs are distributed through the whole year, with maximum frequencies in winter and summer. Interestingly, the decade 1988–1997 did not record any extreme episode and summer extremes were recorded only before 1983. The associated synoptic patterns were classified into four clusters by applying the Ward's hierarchical clustering method to sea level pressure and Z500 data. Four clusters are identified: two represent warm periods in winter, one those occurring spring, especially in March, and another one mainly reflecting summer heat waves. In general, it is found that EWPs are associated with statistically significant anomalies in regional circulation. A deep trough of geopotential height in 500 hPa over North Africa and a ridge directly over the study area were the more important causes for the occurrence of EWPs. Other synoptic configurations that favour extreme periods in winter and summer include, respectively, the northward expansion of the Sudan low pressure with an associated southerly wind advection and the persistence of anticyclonic circulation at all tropospheric levels enhancing subsidence and adiabatic heating. The spring pattern is the most frequent one (nearly 48% of all cases) and reflects a southeastward extension of the subpolar low pressure that leads to the displacement of the Siberian high to south and southwestern Asia and the accompanied northward expansion of the Sudan low.