Extreme heat events in mainland China from 1981 to 2015: Spatial patterns, temporal trends, and urbanization impacts

Extreme heat events have raised public concerns due to their severe adverse effects on both natural and human systems, particularly in urban areas, where they interact with urban heat island effects. Here, we used spatial grouping and statistical models to quantify the spatial patterns, temporal trends, and influencing factors of extreme heat events in mainland China from 1981 to 2015 based on data from 828 weather stations that were downloaded from the National Meteorological Information Center of China. Extreme heat events were defined as days when the heat index exceeded 40.6 °C, at which health risks reach a dangerous level. We found weather stations can be spatially categorized into four groups based on the characteristics of heat events: few events, high frequency, high intensity, and long duration from north to south. Temporal trends in extreme heat events vary across biomes, and the most significant increasing trends were found in Tropical & Subtropical Moist Broadleaf Forests and Temperate Broadleaf & Mixed Forests. Urbanization positively affected the increase in hot days, while station relocation partially offset the effects because stations were moved to less urbanized areas. Results provide valuable insights for public health interventions and the design of sustainable cities and society.