Original title: Concurrent daytime and nighttime heatwaves in the late 21st century over the CORDEX-East Asia phase 2 domain using multi-GCM and multi-RCM chains
Young-Hyun Kim, Joong-Bae Ahn, Myoung-Seok Suh, Dong-Hyun Cha +4 · September 2026
Heatwaves are much more dangerous to human health when scorching days lead directly into hot nights. When it stays hot after dark, the human body gets less time to recover from heat exposure. To see how these combined daytime and nighttime events will change, researchers ran twelve pairs of global and regional climate models across East Asia. The models track daily temperature highs and lows through the late twenty-first century under different future greenhouse gas emission scenarios. The team found that these non-stop heatwaves will expand in area, become much stronger, and last far longer. Historically, they averaged 10.9 days per year between April and September. Under the highest future emissions scenario, that duration jumps to 3 months. Areas facing especially large increases include Indochina, India, and East and West China, bringing unprecedented heat stress to the region.
Imagine a summer day where the temperature stays hot even after sunset. Normally, the night gives you a break to cool down. But if the night is also hot, your body never recovers, and the heat builds up day after day. In this paper, the researchers study when both day and night are hot simultaneously, which is far more dangerous than either alone.
When heat persists through the night, the body gets no chance to cool down. This study shows that by the end of the century, under high emissions, East Asia could experience such conditions for up to three months each year. That means millions of people would face continuous heat stress with little relief, increasing risks of heat-related illness and death.
The abstract doesn't explicitly discuss limitations, but the study is limited to East Asia, specific emission scenarios, and the April–September period. The 25-km resolution may not capture local-scale variations. It does not account for adaptation or mitigation beyond the prescribed pathways.
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Concurrent daytime and nighttime heatwaves in the late 21st century over the CORDEX-East Asia phase 2 domain using multi-GCM and multi-RCM chains — Young-Hyun Kim, Joong-Bae Ahn, Myoung-Seok Suh et al.
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.