Thick clouds will set in over the country from west to east as the week begins, bringing showers and thunder storms across much of the country, the DWD said from its headquarters in Offenbach.
But temperatures will remain pleasant between 15 and 19 degrees Celsius in most areas.
Residents can expect more rain overnight, with a few scattered thunderstorms, as temperatures drop to lows of between 5 and 10 degrees.
By Tuesday rain will only be likely in the Alps, with temperatures topping out between 15 degrees in the northeast and 21 degrees in the south, the DWD said.
Meanwhile Wednesday will be dry and balmy, with highs between 17 and 20 degrees in the north, and a summery 22 to 25 degrees in the south.