Today, the high pressure influence has slowly eased and the upper air flow has turned to the southwest. On the southern side of the Alps, a so-called “retour d’est” brought slightly more humid air from the Po Valley to the Alps. In the other regions, only a few high clouds passing by briefly obscured the sun. There were also a few cumulus clouds along the foothills of the Alps and over the Jura.
The maximum temperatures reached values of around 20 to 24, locally 25 degrees. The strong and long-lasting solar radiation was generally able to warm the soil well. However, part of the heat energy was used for the evaporation of the remaining soil moisture. If the soil had been drier, we would have achieved slightly higher maximum temperatures together with the advection of the warm air mass from the southwest.
It was also mostly sunny in the Freiburg Prealps in the photo Porsel
It was also mostly sunny in the Freiburg Prealps, in the photo Porsel. (Photo: Meteomeldung/APP)
First day of summer 2023 in Basel
The 25-degree mark was broken in Basel with 25.2 degrees. Until yesterday, no temperatures had reached 25 degrees anywhere in Switzerland this year. In Basel, therefore, today was the first
summer day
of the current year. This corresponds very well to the climatology, normally the first day of summer in Basel is reached around May 2nd:
Date (median) of the first summer day of the year at selected switzerland phone number library stations in the lowlands. Days with a maximum daily temperature of 25 degrees or more are counted as summer days.
Date (median) of the first summer day of the year at selected stations in the lowlands. Days with a maximum daily temperature of 25 degrees or more are counted as summer days.
The graph above shows the median date
of the first day of summer; in half of the years the first day click the translucenttb icon on the taskbar of summer occurs before this date, and in the other half after this date.
In Basel/Binningen (BAS), the first day of summer occurs adb directory between April 26 and May 10 in 40% of years. 30% of cases occur before the first date or after the second date.
The next “exceeding” of the 25-degree mark is expected tomorrow in southern Ticino, and probably over a wider area on Saturday. Candidates for this are Valais, Ticino and the Lake Geneva region.