In April and May 2023, Southeast Asia (SEA) encountered an exceptional heatwave. The Continental SEA was hardest hit, where all the countries broke their highest temperature records with measurements exceeding 42 °C, and Thailand set the region’s new record of 49 °C. This study provides a comprehensive analysis of this event by investigating its spatiotemporal evolution, physical mechanisms, forecast performance, return period, and extensive impacts. The enhanced high-pressure influenced by tropical waves, moisture deficiency and strong land-atmosphere coupling are considered as the key drivers to this extreme heatwave event. The ECMWF exhibited limited forecast skills for the reduced soil moisture and failed to capture the land-atmosphere coupling, leading to a severe underestimation of the heatwave’s intensity. Although the return period of this heatwave event is 129 years based on the rarity of temperature records, the combination of near-surface drying and soil moisture deficiency that triggered strong positive land-atmosphere feedback and rapid warming was extremely uncommon, with an occurrence probability of just 0.08%. These analyses underscore the exceptional nature of this unparalleled heatwave event and its underlying physical mechanisms, revealing its broad impacts, including significant health repercussions, a marked increase in wildfires, and diminished agricultural yields.

2023 年 4 月和 5 月，东南亚 （SEA） 遭遇了异常热浪。大陆海受灾最严重，所有国家都打破了最高气温记录，测量值超过 42 °C，泰国创下了该地区 49 °C 的新纪录。 本研究通过调查该事件的时空演变、物理机制、预测性能、重现期和广泛影响，对这一事件进行了全面的分析。受热带波影响的高压增强、水分缺乏和强烈的陆地-大气耦合被认为是这一极端热浪事件的关键驱动因素。ECMWF 对土壤水分减少的预报技能有限，未能捕捉到陆地-大气耦合，导致严重低估了热浪的强度。尽管根据温度记录的稀有性，这次热浪事件的重现期为 129 年，但引发强烈正陆地大气反馈和快速变暖的近地表干燥和土壤水分缺乏的组合极为罕见，发生概率仅为 0.08%。这些分析强调了这一无与伦比的热浪事件的特殊性质及其潜在的物理机制，揭示了其广泛的影响，包括对健康的重大影响、野火的显着增加和农业产量的下降。