As high pressure dominates across central Europe, extreme heat has already been building in paces including Spain, Portugal and France. The French city of Nimes recorded its highest ever August temperature on Sunday of 41.8C (107F). Red extreme heat warnings in south-west France remain in place through Monday and Tuesday.

But what counts as a heatwave? According to the Met Office, a heatwave is an extended period of hot weather relative to the expected conditions of the area at that time of year, which may be accompanied by high humidity.