Projected Changes in Persistent Heat Events and Cold Waves over Central China Based on a Dynamical–Statistical Downscaling Dataset

Abstract Persistent heat events and cold waves not only pose severe threats to human health and ecosystems, but are also closely linked to agricultural productivity, transportation systems, and energy supply. Using a high-resolution (6.25 km) dynamical–statistical downscaling dataset, we first evaluated the performance of individual models and their multi-model ensemble (MME)in reproducing the spatial climatology of daily mean, maximum, and minimum temperatures. Changes in persistent heat events and cold waves over Central China were then projected under three Representative Concentration Pathway (RCP) scenarios (RCP2.6, RCP4.5, and RCP8.5) relative to the baseline period (1986–2005). Results show that both individual models and MME can well reproduce the observed spatial patterns, despite a systematic cold bias. Regional persistent heat events are projected to increase markedly in frequency, intensity, duration, and to expand in spatial coverage, particularly under the higher-emission scenarios (RCP4.5 and RCP8.5), with the annual occurrence frequency increasing by approximately 1.5–3.0 events per year under RCP4.5 and by about 3.0–4.0 events per year under RCP8.5. The hot season is projected to start earlier and end later, extending by 1–2 months under RCP4.5 and RCP8.5. Under RCP8.5, the duration of individual heat events in the mid-to-late 21st century is projected to increase by 10–20 days, and nearly half of the region will experience concurrent high temperatures (≥ 35°C). The area from eastern Hubei Province to central Hunan Province is identified as the zone with the highest risk of persistent heat events. In contrast, the annual frequency of cold waves is projected to decline to less than one event per year under all three scenarios in the late 21st century, while extreme minimum temperatures are projected to rise substantially. Cold waves over Central China are projected to evolve toward lower occurrence frequency, a shorter cold-wave season, and shorter individual event duration. Under the high-emission scenario, this reduction in cold‑wave frequency extends across most of Central China, and becomes more widespread and pronounced in the late 21st century than in the mid‑21st century.