Distinct intraseasonal pathways driving rapidly escalating heat extremes in North China and their subseasonal predictability

Rapidly escalating heat extremes, characterized by abrupt onset and limited preparation time, pose disproportionate risks to public health, agriculture, and regional economies, yet their governing mechanisms and subseasonal predictability remain poorly understood. Here we identify 107 such events over North China during the summers of 1940–2024 and classify them into four spatial types. Thermodynamic and circulation analyses show that rapid warming arises from different combinations of horizontal warm advection and subsidence-induced adiabatic heating. The four types are linked to distinct intraseasonal circulation patterns involving tropical convection, mid–high-latitude wave trains, or their interference. Forecasts from subseasonal-to-seasonal dynamical prediction systems show a consistent hierarchy: events driven mainly by tropical intraseasonal variability are the most predictable, whereas events associated with two extratropical wave trains have the lowest skill. These results establish a process-based framework linking intraseasonal dynamics to rapid heat escalation and provide a physical basis for improving subseasonal prediction of high-impact heat extremes. Rapidly escalating heat extremes in North China are classified into four types with distinct intraseasonal physical pathways, with tropical-driven events showing the highest predictability and dual-extratropical-wave-train events the lowest, as revealed by observations and climate model experiments.