MétéoSuisse has issued warnings of extremely high temperatures from midday today until Wednesday evening in Swiss Romande and the canton of Ticino.
Tomorrow is predicted to be the hottest day, with temperatures of 38 and 39 degrees Celsius expected in Geneva.
The rest of Swiss Romande below 800 metres altitude will also be scorching hot, with temperatures of 36 and 37 degrees Celsius.
Night-time temperatures are expected to stay around 20 to 23 degrees, making sleeping difficult and uncomfortable for many.
The high-pressure weather system due to arrive in Switzerland tomorrow has led to loss of life and wildfires in several parts of Europe.