Heavy rain showers, storms and even hailstorms are to be expected, as well as top temperatures of up to 27 degrees Celsius.
The German weather service said at the weekend that the northern part of the country would remain dry and bright but at times overcast, with top temperatures between 17 and 21 degrees Celsius.
Central regions will get rain, while the south will be hit with showers and storms, with top temperatures of up to 25 degrees Celsius.
Tuesday will see the north and northeast mostly sunny, with temperatures up to 24 degrees Celsius.
Central and southern Germany will have more clouds, with showers and storms to be expected, although temperatures will rise as high as 27 degrees Celsius in the south.
The south will retain the high temperatures on Wednesday, with the weather service warning of strong showers and storms with hail in places. The north will remain sunny without such extreme weather.