The Hessians expect sultry days and tropical nights over the weekend.
The next few days will be a "very hot affair," said a meteorologist from the German Weather Service (DWD) on Thursday.
The maximum temperatures on Thursday and Friday are 36 degrees.
At the weekend it gets a little colder, but even then up to 33 degrees are possible.
The DWD warns of a strong heat load.
During the night the temperatures in Hesse were still below 20 degrees on Thursday, but that will change in the next few days, according to the meteorologist. So-called tropical nights are particularly possible in metropolitan areas. There is then a risk of thunderstorms, especially on Friday and Sunday. There could be gusts of wind, hail or heavy rain locally.