Interdecadal variability and future persistence of meteorological drought in Yunnan, Southwest China (1961–2021)

Yunnan Province, Southwest China, located at the intersection of the South and East Asian monsoon systems, is highly vulnerable to hydro-meteorological drought due to its monsoon climate, complex topography, and dense population. Drought threatens regional water resources, socio-economic stability, and ecological security under ongoing global warming. This study used monthly meteorological observations from 124 stations across Yunnan Province during 1961–2021. Based on these data, the 12-month Standardized Precipitation Evapotranspiration Index (SPEI-12) was computed using potential evapotranspiration (PET) from the CRU TS v4.07 dataset. Intensity analysis was applied to identify interdecadal wet–dry transitions, and the Hurst exponent was used to assess drought persistence and future trends. SPEI-12 shows a long-term decline, with an abrupt shift around 2002 marking intensified drought. Drought strengthened after 2000, especially during 2000–2010; 2010–2021 was the driest period. Notable wet-dry transitions also occurred in 1961–1970. Reduced precipitation, rising temperature, increased PET, weakening South Asian monsoon, and large-scale ocean–atmosphere modes (PDO, AMO), were key natural drivers in shaping regional drought patterns. Urbanization and land-use change further amplified regional drought severity. Hurst analysis indicates persistent drought over the next three decades, with most of Yunnan, particularly eastern and western regions, expected to experience further SPEI-12 declines. These findings offer guidance for drought monitoring, water management, and regional adaptation planning. • SPEI-12 shows long-term drying with an abrupt shift around 2002; 2000–2010 was the driest decade. • Hurst exponent predicts continued drought persistence over next three decades. • Precipitation dominates drought variations; temperature, PET, AMO, PDO, and human activity contribute.