High-resolution projections of extreme heat and thermal stress in southeastern U.S.

Considering the increasing frequency, severity, and societal impacts of extreme heat under climate change, understanding the regional dynamics of extreme heat is critical for informing public health preparedness and energy system planning. This study investigates the spatial characteristics, dominant drivers, and future evolution of extreme heat days in North Carolina (NC) and Virginia (VA) using high-resolution simulations from the Weather Research and Forecasting (WRF) model based on the Pseudo Global Warming (PGW) method. The analysis of May to September in the two base years, 2010 and 2011, reveals different heat mechanisms. Extreme heats in 2010 are primarily associated with weak synoptic anomalies, whereas the extreme heats in 2011 exhibit stronger land–atmosphere coupling, characterized by soil moisture depletion. Based on these two distinct types of heat mechanisms, projections comparing the current climate (2000-2020) with the late-century period (2060-2089) under three Shared Socioeconomic Pathways (SSP1-2.6, SSP2-4.5, SSP5-8.5) indicate different increases in daily 2-m maximum temperature ranging from 1.6 °C to over 4.4 °C. These temperature changes are driven by variations in radiative forcing, atmospheric circulation, and land surface conditions. The frequency, duration, and severity of extreme heat days exhibit a nonlinear escalation under the three scenarios. “Danger” and “Extreme Danger” heat days are projected to emerge under SSP5-8.5, underscoring the urgent need for aggressive mitigation and tailored adaptation strategies to reduce thermal stress risks in this region.