Spatiotemporal Characteristics of Hourly Extreme Precipitation and the Effects of Urbanization in Yunnan, China

. Hourly extreme precipitation (HEP) events were defined using the 99.9% percentile threshold, and the spatiotemporal characteristics and the effects of urbanization on HEP under complex terrain conditions in Yunnan were investigated by using hourly precipitation data from 125 national meteorological observation stations for 1980–2022 and 1135 regional stations for 2010–2022 in Yunnan, along with socioeconomic, land-use, and nighttime lighting data. The results show that the distribution of the HEP index was the highest in the southern border region, whereas it was relatively low in the northwestern region in Yunnan. The highest HEP contribution rate, exceeding 19%, was observed in central and eastern Yunnan. The characteristics of HEP daily variation indicate a bimodal pattern, with peak periods at 17:00–20:00 and 02:00–05:00, and valley periods at 11:00–14:00. The high HEP contribution rate and frequency occur in summer, with a contribution rate exceeding 20%. The HEP frequency in July and August reached 2.0 times. Compared with those during 1980–2022, the daily and monthly variations of the HEP index were stronger during 2010–2022, and the frequency and contribution rate in summer were more concentrated. The analysis of the impact of urbanization on HEP revealed that during the period of slow urbanization in 1980–2006, the increase in the HEP index at urban stations was slightly higher than at suburban stations. However, during the rapidly developing period of 2007–2022, the HEP index increase rate of urban stations was 2–3 times that of suburban stations. The daily and monthly variations of the HEP index during the rapid development stage were higher than during the slow development stage. These results offer a scientific basis for a deeper understanding of how HEP characteristics change under complex terrain conditions and provide important support for climate risk prevention and adaptive planning in cities in the plateau region.