Cool, damp air moving over Germany from the west means temperatures will barely scrape into double figures across much of the land, the DWD said.
The northwest should brace for particularly miserable conditions at the start of the long holiday weekend, with Thursday bringing sleet and even snow above 400 to 600 metres elevation.
A band of better weather, including sunshine, will stretch from northern Baden-Württemberg and Bavaria to Saxony-Anhalt and Brandenburg as far as Mecklenberg Western-Pomerania.
Upper temperatures will sit between 7 and 11 degrees Celsius, reaching 13 in parts of the Lausitz and southern Brandenburg regions.
Thursday night will bring rain and temperatures as low as -4 degrees in the Allgäu region of southwestern Bavaria, with the northwest enjoying the mildest conditions with lows of about 2 degrees.
Friday will be largely cloudy with only parts of the east seeing much sunshine and maximum temperatures languishing between 9 and 13 degrees.
On Saturday, weather in the west will remain cloudy and changeable, with patches of rain. Eastern parts of the country will however enjoy frequent sunshine and remain mostly dry.
Maximum temperatures will again range from 9 to 13 degrees, though the sunshine in lucky parts of the east will push the maximum up to 15 degrees.