Wednesday afternoon and evening will see mild temperatures of between 15C and 19C in the north and 19C to 25C in the south, said German weather service DWD. The North Sea islands will see the lowest temperatures, at a chilly 12C.
The north is set to stay dry, but by the evening a strong wind will spring up - of up to 75kph on the North Sea coast - and carry on overnight into Thursday. The odd crack of thunder may be heard in the southeast on Wednesday afternoon, heralding more unsettled weather towards the end of the week.
Thursday will be more unsettled, with the odd shower in the south and east. But temperatures will remain high, with up to 26C expected in the south and lows of 13C on the border with Denmark.
Building pressure will break overnight into Friday with showers and odd cracks of thunder forecast for the south east and rain in south. The north, meanwhile, will remain clear and dry.
Friday will see the rain in the south continue and temperatures begin to drop to highs of between 10C and 17C, and even cooler on the coast and in higher areas. Further north isolated showers will give way to longer sunny spells, especially on the coast.
Overnight to Saturday will see temperatures really take a nosedive, down to between 1C to 7C degrees, with even a slight chance of ground frost for northwestern Germany. The south will see more rain and even some snow in the high alps. Elsewhere skies should remain cloudy, but dry.
Saturday will be cooler than the rest of the week, with highs of 6C to 15C degrees and changeable cloud and sunny spells. Localised showers are forecast for the coast and in the lower lying Alpine regions, but elsewhere it should stay dry.
And winter will stage a mini-comeback overnight into Sunday, with temps down to 4C in the south east and a chilly -2C in the north west.