Linking High‐Amplitude Quasi‐Stationary Waves With Concurrent Humid‐Heat Extremes in a Warming World

Abstract Humid‐heat extremes pose serious risks to human health. When occurring simultaneously across different regions, they can lead to widespread exposure and substantial economic loss. Previous studies have linked concurrent humid‐heat extremes in the Northern Hemisphere midlatitudes to high‐amplitude quasi‐stationary waves (QSWs). However, how these waves respond to climate warming remains unclear, limiting our ability to assess future risks quantitatively. Using a single model initial‐condition large ensemble, we find that the climatological‐mean amplitude of wavenumbers 3 and 7 QSWs increases in late summer as the climate warms, along with more frequent high‐amplitude Wave‐3 and Wave‐7 events. These changes are associated with increased regional frequencies of humid‐heat extremes, particularly in regions with strong historical connections between humid‐heat extremes and high‐amplitude QSWs. Our findings help identify regions characterized by high‐impact concurrent humid‐heat extremes and improve understanding of spatially heterogeneous changes in humid‐heat extremes in a warming climate.