Higher Probability of Occurrence of Hotter and Shorter Heat Waves Followed by Heavy Rainfall

The consecutive heat wave and heavy rainfall (CHWHR) events, defined as the occurrence of heat waves followed by heavy rainfall, can cause more damages than individual extremes. Nevertheless, this type of compound event has not been diagnosed systematically. Here we examine the occurrence of CHWHR events and underlying characteristics. We find 22% of land areas experienced statistically significant CHWHR events within 7 days in China during 1981–2005, with an average 26% of heat waves being followed by heavy rainfall (vs. 10% expected by chance). More importantly, the shorter and hotter heat waves are more likely to be followed by heavy rainfall than other heat waves. This phenomenon is associated with atmospheric convection and moisture convergence. In addition, climate projection shows the CHWHR events will occur more frequently and abruptly in China throughout the 21st century, which contribute to the increased compound risk of back-to-back heat waves and flash floods.