Enhanced Adiabatic Heating Drives Faster Warming of Early Summer Hot Extremes in North China

Abstract North China has recently seen frequent hot days above 35°C or even 40°C before or at the very beginning of June. This raises a concern about the changing seasonality of exceptional hot extremes in the region which might leave population there underprepared. Based on station observations, we found that since 1990 early summer hot extremes have warmed 2–3 times faster than those in peak and late summer stages. A Lagrangian decomposition points to the main driver for the intra‐seasonally disproportionate warming rates as the enhanced adiabatic heating, contributed by more frequent arrival and intensified descent of upper‐level air particles from west and south. We further illustrated that the past‐decade prevalence of a ridge pattern well atop North China was essential to the enhanced adiabatic heating. Our results highlight the critical yet overlooked role of changing atmospheric dynamics in altering regional extremes.