Humid heat extreme (HHE) is a type of compound extreme weather event that poses severe risks to human health. Skillful forecasts of HHE months in advance are crucial for developing strategies to enhance community resilience to extreme events^1,2. This study demonstrates that the frequency of summertime HHE in the southeastern United States (SEUS) can be skillfully predicted 0–1 months in advance using the SPEAR (Seamless system for Prediction and EArth system Research) seasonal forecast system. Sea surface temperatures (SSTs) in the tropical North Atlantic (TNA) basin are identified as the primary driver of this prediction skill. The responses of large-scale atmospheric circulation and winds to anomalous warm SSTs in the TNA favor the transport of heat and moisture from the Gulf of Mexico to the SEUS. This research underscores the role of slowly varying sea surface conditions in modifying large-scale environments, thereby contributing to the skillful prediction of HHE in the SEUS. The results of this study have potential applications in the development of early warning systems for HHE.

极端湿热（HHE）是一种对人类健康构成严重威胁的复合极端天气事件。提前几个月对 HHE 进行熟练的预测对于制定增强社区应对极端事件的能力的战略至关重要^1,2 。这项研究表明，使用 SPEAR（无缝预测系统和 EArth 系统研究）季节性预报系统可以提前 0-1 个月巧妙地预测美国东南部 (SEUS) 夏季 HHE 的频率。热带北大西洋 (TNA) 盆地的海面温度 (SST) 被认为是这种预测技能的主要驱动因素。大规模大气环流和风对 TNA 异常温暖海温的响应有利于热量和湿气从墨西哥湾向 SEUS 的输送。这项研究强调了缓慢变化的海面条件在改变大尺度环境中的作用，从而有助于在 SEUS 中巧妙地预测 HHE。这项研究的结果在 HHE 早期预警系统的开发中具有潜在的应用价值。