Analysis of variations in 12 extreme temperature indices at 68 meteorological stations on the Yunnan-Guizhou Plateau (YGP) in southwestern China during 1960–2019 revealed widespread significant changes in all temperature indices. The temperature of the hottest days and coldest nights show significantly increasing trends, and the frequencies of the warm days and nights also present similar trends. The temperature of the coldest night has a significant and strong warming trend (0.38 °C/decade), whereas the frequency of frost days shows the fastest decrease (1.5 days/decade). Increases in the summer days are statistically significant, while a decreasing trend for the diurnal temperature range is not significant. Furthermore, there were significant differences in the changes of temperature indices between 1960–1989 and 1990–2019. Most parts of the YGP underwent significant warning, manifesting that the mountainous regions are relatively sensitive and vulnerable to climate change. The correlation coefficients between the temperature indices and various geographical factors (latitude, longitude, and height) reflect the complexity of regional temperature variability and indicate enhanced sensitivity of extreme temperatures to geographical factors on the YGP. It was also found that extreme temperatures generally had weaker correlations with the El Nino-Southern Oscillation, North Pacific Index, Southern Oscillation Index, North Atlantic Oscillation, and East Asian Summer Monsoon Index than with the South Asian summer monsoon index, Nino4 indices and Arctic Oscillation, and there were more insignificant correlations. Regional trends of the extreme temperature indices reflect the non-uniform temperature change over the YGP, which is due to the complex interaction between atmospheric circulation patterns and local topography. The results of this study have important practical significance for mitigating the adverse effects of extreme climatic changes, in particular for the YGP with its typical karst geomorphology and fragile ecological environment.

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Light precipitation events are an essential feature of rainfall for agricultural production, risk prediction of drought or flood disasters, and natural resource management in a certain area. We investigated the spatiotemporal variations in light precipitation events with intensities of 0.1–10 mm/day, based on daily precipitation data for the Yellow River Basin (YRB), China, during 1960–2018, and explored their relationships with large-scale atmospheric circulation patterns (LSACPs) and altitude. For further analysis of the changes in the light precipitation events, we classified light rain (0.1 ≤ P < 10.0 mm/day) into five grades of intensity by using equal interval division. Results indicate that the mean annual light precipitation amount and days were 182.7 mm and 80 days, respectively, from 1960 to 2018 over the YRB, accounting for 39.2% and 85.2% of the total annual precipitation amount and days, respectively. Both the amount of light rain and the number of light precipitation days declined by −1.3 mm/decade and −1.4 days/decade, respectively, and suggested that most rain events were of low intensity (0.1 ≤ P < 2.0 mm/day). Light precipitation events mainly occurred in the upper and middle reaches of the YRB and decreased from the southwest to the north. Additionally, changes in light rain events appear to be complex and possibly related to LSACPs and altitude. We found that the LSACPs were a possible mechanism for light precipitation events in the YRB over the past decades. With increasing elevation, light precipitation events decreased significantly throughout the study period. Thus, the decrease in precipitation days mainly occurred at lower altitudes in the YRB. The results also reflect the complexity of regional climate change in the YRB because atmospheric circulation related to climate phenomena not only causes the complex variation in precipitation but also changes its altitude dependence.