Rapid Indian Ocean warming fuels more frequent extreme pre-flood season rainfall over southern China.

In 2024, southern China faced its worst flooding during the pre-flood season (April-June), the first major rainfall season in East Asia, with considerable socioeconomic consequences. This extreme flooding is fueled by the unprecedented warming in the Indian Ocean, with a decaying moderate El Niño in the Pacific contributing weakly. Alarmingly, similar pre-flood season flooding events have become increasingly frequent in southern China over recent decades, posing unexpected risks to local communities. We demonstrate that the recent rapid Indian Ocean warming enhances local convection efficiency, leading to more frequent intense pre-flood season rainfall. As sea surface temperature in the Indian Ocean continues to rise in a warming world, it becomes increasingly crucial to understand its role in shaping regional extreme weather patterns for future climate adaptation and disaster management.