contents
A heat wave has been plaguing us since Wednesday. 36.6 degrees were reached in Biasca on Friday and 35.5 degrees in Basel on Saturday. A tropical night followed in many places. The temperatures did not drop below 20 degrees. It could get even hotter on Sunday afternoon with the coming foehn.
Legend:
stop the heat
Evening cooling off in the Rhine near Basel. During the day the thermometer showed up to 35.5 degrees.
Peter Wehrli
Since Wednesday afternoon temperatures in Switzerland have mostly been above 30 degrees. There was a first foretaste of the heat wave on Wednesday afternoon in Sion with 34.4 degrees. On Friday it got extremely hot with a north föhn wind, especially in the south. With 36.6 degrees in Biasca, thanks to north foehn support, the highest June temperature since measurements began. However, measurements have only been taken in Biasca since September 2017. On Saturday it was particularly hot in the north. In Basel, the thermometer showed 35.5 degrees. That was the highest value north of the Alps in 2022. It was also very hot in Visp with 35.4 degrees and in Delsberg with 35.0 degrees. In some cases even higher values were reported, but these were not measured at an official station with a reference.
Legend:
bowl
It was never colder than 18.2 degrees on the bowl all night, just not enough for a tropical night.
Elias Frey
The night of nights
In numerous places in Switzerland there was a so-called tropical night in the night from Saturday to Sunday. This means that the temperature did not drop below 20 degrees all night. In the foehn areas and in slightly elevated locations, the temperature sometimes did not drop below 22 degrees, such as in Bad Ragaz/SG and in Sevelen/SG or in Evionnaz/VS. There was also a tropical night on Lake Geneva and Lake Neuchâtel or on the Jura mountains, for example in Rünenberg/BL. Even more spectacular than the minimum temperature was the situation at 4 a.m. in the morning. At that time, 28.5 degrees were measured in Gersau and 27.3 degrees in Sevelen.
Legend:
Locarno/TI
With north foehn it was 31.3 degrees in Locarno on Friday.
Irene Eichhorn
Potential for the record
The tropical night also offers a ramp for record temperatures. If the early temperature is not 10 degrees, but more than 20 degrees, higher temperatures are automatically reached in the afternoon. In the early afternoon at 1 a.m., for example, 34.4 degrees were measured in Geneva, but the thermometer also showed 34.0 degrees in Sevelen. In the course of the afternoon, maximum values between 32 and 36 degrees are again expected, in the foehn areas, but also partly along the Jura, 37 degrees are possible. This would mean a new record for the month of June in our country. At the beginning of the coming week it will continue with temperatures of more than 30 degrees. However, it should just not be enough for absolute maximum values.
Legend:
Walenstadt
On Saturday it was cloudless in many places for a long time.
Peter Eicher
What was the highest June temperature so far?
In the official statistics of the state weather service, the 36.9 degrees on June 27, 1947 in Basel are still listed as a record. However, the measurement technology back then was completely different and cannot be compared with today’s instrumentation. With earlier measurement technology, maximum temperatures were automatically higher. During the last June heat wave in 2019, 36.9 degrees were also measured in Sion on June 28 and even 37.0 degrees on June 30. However, these values were subsequently corrected downwards, since the station at Sion Airport no longer corresponded to the international reference.
Legend:
Fiescheralp/Märjelensee.
The Alps have largely snowed out. No wonder, the zero degree limit is around 4300 meters.
Klaus Minning
The hottest time of the year is yet to come
Absolute maximum temperatures in June are rather rare. The hottest phase of the year is usually only reached during the dog days between July 23rd and August 23rd. If you analyze the annual highs in Switzerland in the 21st century more closely, you can see that the annual highs occurred nine times in July, eight times in August and only five times in June, and the absolute highs were also clear in July and August higher than in June. For August, the absolute maximum is 41.5 degrees (2003) and in July it was 39.7 degrees (2015). The current temperatures are rather modest.
Where is the heat coming from?
For days there has been a low pressure area in front of the Portuguese Atlantic coast, where the classic Azores high should actually be at this point in time. The consequence of this is that southerly currents have repeatedly been able to set in from Spain to the Alps in recent weeks. This brought the first hot days in Switzerland about a month ago. Spain has been suffering from constant heat for days. In the Seville – Cordoba area, temperatures are almost constant around 40 degrees with maximum values of up to 43 degrees. Since the low-pressure area is now shifting towards Biscay, this heat is now moving towards the Alps. Since the sun is not quite as steep here as in Spain, the maximum temperatures are not quite as high. On Saturday, the center of the heat shifted from southern Spain to south-west France. 43 degrees were measured in Biarritz. But there were also 37 degrees near the Swiss border, for example in Colmar in Alsace.