“The end of September is classic time for Altweibersommer. And this year, the weather is actually behaving according to this rule,” said Ansgar Engel of the German Weather Service (DWD). Although the astronomical start to autumn happens on September 23 this year, most meteorologists consider the start of the season September 1.
Nonetheless, Engel said, autumnal signs “can't be completely overridden because of the thick fog fields that are spreading out in lowlands and river valleys, but there's still hope that the strong early autumn sun can mostly dissolve the grey veil by late morning.”
But high pressure system Renee, approaching Germany from over the Atlantic, is bringing a sudden onset of warmer weather which will push temperatures up to between 20 and 25 degrees by Saturday afternoon across most of the country.
Friday will dawn with heavy fog cover in the south, transitioning into cloudy but warm weather. A few cloud constellations will move through the north, but only limited precipitation will interrupt an otherwise dry day. Highs will reach 16 degrees in northern Germany, 21 degrees in southern areas. In addition, most of the country will experience breezy conditions, with a light westerly wind in the north and stronger gusts on the coast.
On Saturday, some early low-lying clouds may only partially dissolve, but otherwise the DWD predicts hot, sunny weather. Only northern Germany may still experience some thicker cloud cover, although it should also remain dry. Temperatures will rain from 18 degrees in the northeast to 23 degrees in the southwest.
Sunday's weather should continue the trend, according to DWD, with warm and sunny conditions appearing after the dissolution of morning fog. Temperatures should continue to climb, reaching 20 degrees in the north and 25 in parts of southern Germany.