A weak gradient disturbance will make itself felt over Germany at the start of the first week of September with increasing shower and thunderstorm activity. While the midsummer weather character will remain over the east of Germany, heavy, persistent rain may occur over the south.
BThe first thunderstorms were already noticeable in the night from the southwest over the Black Forest and southern Baden-Württemberg and will spread further north and east during the day, roughly south of a line from Bremen and Dresden. The thunderstorms can sometimes be more intense and cause severe weather events in some places (thunderstorm radar || warning report). Further to the northeast and east it will remain dry and generally sunny. The wind is light from different directions and can become gusty or stormy near thunderstorms. Temperatures will reach +25 to +30 degrees and will drop to +20 degrees near thunderstorms.
Humid and warm September weather with further showers and thunderstorms
An unstable layered air mass is expanding further and further across Germany. September 3rd (Tuesday) begins with sunshine, which quickly becomes cloudy from the west. Showers and thunderstorms will then occur in the area west of a line from Hamburg and Munich, but these will be more local and regional rather than widespread. Nevertheless, storm-like weather phenomena with lightning and hail, heavy rain and stormy gusts of wind can occur. Further east, calm and generally sunny September weather can be expected, although the occasional thunderstorm cannot be completely ruled out. The wind will be light from various directions and temperatures will reach +22 to +26 degrees, with longer periods of sunshine up to +28 degrees, and may make mid-summer temperatures of up to +34 degrees possible over Mecklenburg-Western Pomerania, Saxony-Anhalt, Brandenburg, Berlin and Saxony.
Air mass boundary with severe weather potential over Germany
The heat will retreat further east on September 4th (Wednesday) and will dominate the federal states of Mecklenburg-Western Pomerania, Berlin, Brandenburg, Saxony-Anhalt and Saxony with temperatures of +30 to +35 degrees. Further west, a thunderstorm cluster will move in and, with quasi-stationary behavior, will cause prolonged – thunderstorm – precipitation. In some places, local flash floods and regional flooding cannot be ruled out. The thunderstorm front will fail due to the high pressure and will advance eastwards to a line from Rostock and Dresden. While the sky to the west will be mostly heavily overcast with temperatures of +20 to +25 degrees, unbridled sunshine can be expected to the east. The wind can become gusty at times, coming from different directions.
The potential for prolonged heavy rain over the southern parts of the country
Whether this will happen remains to be seen and depends largely on the positioning of a weak disturbance. It cannot be ruled out that the heavy precipitation area will extend from the Alps across the south of Germany and could lead to long-lasting and heavy rainfall on both 5 and 6 September (Thursday and Friday), with the focus being on Baden-Württemberg and Bavaria. Further north, precipitation activity will decrease and the sun will appear more frequently as the clouds clear. North of a line from Cologne and Berlin, this could be the case with a completely cloud-free sky. Temperatures in the south will reach between +18 and +24 degrees, depending on the intensity of the precipitation. Further north, temperatures of up to +28 degrees and to the east up to +34 degrees are possible. The temperature distribution alone shows how important the positioning of the disturbance will be with regard to persistent rain and midsummer.
September between continuous rain and summer weather
The weather on September 7th (Saturday) also depends heavily on how the front behaves in relation to the high pressure system. At the moment, the south of Germany – and thus Bavaria and Baden-Württemberg – remains in the area of influence of the disturbance, which can repeatedly result in precipitation. Further north, the clouds quickly dissipate and the precipitation disappears, and another summery warm and dry September day can be expected. Temperatures will reach +20 to +25 degrees in the south, and between +24 and +28 degrees are possible in the north and up to +30 degrees in the east.
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