The 2025 Asian Summer Monsoon: Excessive Rainfall, High-Impact Weather, and Climate Extremes

The 2025 Asian summer monsoon (ASM) was characterized by excessive monsoon rainfall, an early onset over most subregions, and widespread weather and climate extremes, including exceptionally high temperatures, record-breaking rainfall, and frequent, clustered tropical cyclones. From May to October 2025, many ASM subregions recorded rainfall exceeding climatology by approximately 10–30%, indicating an overall stronger-than-average ASM. Specifically, hot-wet conditions were observed in East and Southeast Asia except in Japan, whereas cool-wet conditions were observed in most of South Asia except in Pakistan. Monsoon onset was generally earlier than normal except in the South China Sea, although the Indian summer monsoon's northward progression was slow with a distinct mid-summer hiatus. North China experienced a remarkable 76% rainfall surplus and an abnormally prolonged rainy season. These ASM behaviors and associated extreme events caused severe social impacts and substantial economic losses, underscoring the urgent need to advance understanding of seasonal and intraseasonal variability and to improve the predictability and warning systems for ASM and associated extremes.