The 2024 Asian–Australian Monsoon Year: Widespread Extremes with Notable Subseasonal Variability and Socioeconomic Impacts

The 2024 Asian–Australian monsoon (AAM) year, defined from April 2024 to March 2025, was notable. A prolonged rainy season was observed in most parts of the AAM region based on the available sources, except for Meiyu, the second stage of the East Asian summer monsoon. The rainy season also featured elevated near-surface air temperatures, a boreal summer rainfall surplus of approximately 20% across South, East, and Mainland Southeast Asian regions, an austral summer rainfall deficit of approximately 30% in northern Australia, and a surplus of around 30% in the Maritime Continent. During boreal winter, a strong East Asian winter monsoon circulation resulted in below-average precipitation along East Asia's climatological rainbelt, including South China and Japan, accompanied by above-average near-surface air temperatures. Meanwhile, the 2024 AAM exhibited notable subseasonal variability, with abrupt alternations between dry/drought and wet/flood conditions, as well as between warm and cold episodes in many regions. It was also characterized by widespread extremes, including but not limited to heavy rainfall, heatwaves, cold surges, and tropical cyclones. These AAM-associated variability and extremes exerted considerable social impacts and caused substantial economic losses, highlighting the ongoing challenges in understanding and predicting the AAM on regional and multiple timescales.