A heatwave is defined by the World Meteorological Organization (WMO) as a ‘period where local excess heat accumulates over a sequence of unusually hot days and nights’.
Heatwaves increase many risks, affect health, slow down business. They increase mortality and cause drought and uncontrolled fires; water quality deteriorates and agricultural crops wilt irreversibly. They affect the weak and infirm disproportionally and those exposed to the sun, such as farm workers. According to the WMO, they are 30 times more likely to occur with climate change.