This project, which is part of a broader WHO/UNDP Global Environment Facility (GEF)-funded project, developed and implemented a heatwave early warning system to reduce the health risks and to increase the capacity of health systems and community residents to prepare for and cope with periods of extreme temperatures. The project was piloted in four cities: Harbin, Nanjing, Shenzhen and Chongqing, located in different climate zones within China.