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With a warming climate, temperature extremes have been a main global issue in recent decades due to their potential influence on the sustainable development of human life and natural ecosystems. In this study, 12 indicators of extreme temperature events are used to evaluate the spatiotemporal distribution, periodic structure and teleconnections with large-scale atmospheric circulation in Xinjiang, Northwest China by combining wavelet coherence (WTC) analysis based on continuous wavelet transform (CWT) analysis with the sequential Mann-Kendall test. We find that over the past six decades, the climate in Xinjiang has become warmer and has suffered from increases in the frequency of warm extremes and decreases in the frequency of cold extremes. Warm extremes have mainly occurred in the southern Tianshan Mountains surrounding the Tarim Basin and western part of the Taklamakan Desert, and cold extremes have primarily occurred in the southwestern Altai Mountains and northern foot of the Tianshan Mountains. Extreme temperature events, including warm extremes, cold extremes, and other temperature indices, have significant interannual variability, with the main oscillation periods at smaller (2–4-year band), intermediate (4–7-year band), and greater time scales in recent decades. Furthermore, cold-extreme indices, including frost days, cool days, and cool nights all show a clear changepoint during 1990–1997 at the 95% confidence level, and both ice days and cold spell duration indicator have a potential changepoint during 1981–1986. However, the changing points for warmextreme indices are detected during 1992–1998. The temperature variables are significantly correlated with the EI Niño-Southern Oscillation (ENSO) and Arctic Oscillation (AO), but less well correlated with the Pacific Decadal Oscillation (PDO). The phase difference in the WTC spectra is not uniform between temperature extremes and climatic oscillations. Our findings will have important implications for local governments in taking effective measures to mitigate the potential effects of regional climate warming due to human activities in Xinjiang. [ABSTRACT FROM AUTHOR]

• Climate change has increased extreme precipitation in Xinjiang over the past 60 years. • Extreme precipitation events have clear oscillation periods at the 2–4-year band. • The Q a values for nine natural rivers have dominant periodicities of 2–7 years. • Increasing extreme precipitation events significantly affect streamflow fluctuation. • SSN and ENSO-modulated precipitation anomaly contributes to streamflow variation. Solar activity including sunspot number (SSN) and EI Niño-Southern Oscillation (ENSO) affect both surface and subsurface hydrological processes in arid-semiarid regions of the world, thus evaluating multi-scale hydrological response to global climate changes can provide valuable information on regional water resources management and ecological restoration. In this study, we utilize wavelet coherence together with continuous wavelet transform to analyze the influence of SSN and ENSO on multiple interacting hydrological processes and distinguish nonstationary patterns in annual precipitation and extreme precipitation events and their effects on short-term or long-term streamflow variations and periodic flooding in Xinjiang, an arid-semiarid region of China. The results indicate that the climate in Xinjiang has become wetter during the period 1960–2019. Extreme precipitation events in Xinjiang have significant oscillation periods at the 2–4 years band, and stations with strong extreme precipitation events are located in northern Xinjiang and Tianshan mountain area, while stations with weak extreme precipitation events are found in southern Xinjiang. The annual precipitation has significant multiple-periodicities at the 2–7-year band, at the 7–11-year band, and at the 13–15-year band. Furthermore, annual streamflow data for nine natural rivers all have significant dominant periodicities at inter-annual scale of 2–4-year and 4–7-year band, and monthly streamflow data for Yarkand river has significant periodicities at intra-annual scale of 3–7-month and 8–14-month band. Since evolution of annual streamflow variability and monthly streamflow variability all show direct response to precipitation features, increasing extreme precipitation events significantly affect streamflow fluctuation of natural rivers in Xinjiang. Overall, SSN and ENSO is viewed as one of the main drivers for annual precipitation or extreme precipitation periodic variation by either enhancing or suppressing convection, and the SSN and ENSO-modulated precipitation anomaly contributes to significant streamflow variation or regional flooding disasters. Investigating the detailed linkage between interannual to multidecadal climate variability and hydrometeorological variables will help decision-makers and scientists to better understand variability in regional hydrological processes, which has great implications for water resources planning and operations in Xinjiang under future climate uncertainty. [ABSTRACT FROM AUTHOR]