In April and May 2023, Southeast Asia (SEA) experienced an exceptional heatwave, particularly impacting Continental SEA. This study comprehensively analyzes this event, investigating its spatiotemporal evolution, physical mechanisms, forecast performance, return period, and impacts. Enhanced high-pressure systems, moisture deficiency, and strong land-atmosphere coupling are identified as key drivers. The ECMWF model underestimated the heatwave's intensity due to limited forecast skills regarding soil moisture and land-atmosphere coupling. While the return period is estimated at 129 years based on temperature records, the combined probability of near-surface drying and soil moisture deficiency is only 0.08%. Broad impacts included health issues, increased wildfires, and reduced agricultural yields.

Yang Lyu, Jingyu Wang, Xiefei Zhi, Xianfeng Wang, Hugh Zhang, Yonggang Wen, Edward Park, Joshua Lee, Xia Wan, Shoupeng Zhu, Duc Tran Dung