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It was a record May. On May 20, 2022, for example, it was 33.7 degrees in Bad Ragaz – it has never been this hot in May since measurements began. New records were also reflected in the number of summer days: in Magadino/TI the summer mark of 25 degrees was exceeded 17 times and in Geneva 15 times.
“Normal” May start
From May 1st to May 8th (Mother’s Day), the merry month was unremarkable: sunny and cloudy days alternated, at times there were showers on cooler nights and pleasant warmth during the day – nothing unusual. Then Hoch “Wolf” took over and the May normality came to an end.
May in summer mode
May 10 was the first day of summer in 2022. On this day, the first day of summer (temperature ≥ 25 degrees) was recorded at several weather stations. Only in Chur/GR was there already 25 degrees on April 12th, but with the help of a hair dryer. After that, it went in quick succession. Instead of the dreaded frost, there were summer days during the Eisheilgen from May 12th to 15th and on the day of the cold Sophie, on May 15th, Visp/VS even had the first hot day of 2022 with 30 degrees. On May 20th, heat records tumbled at 12 official weather stations. It was hottest in Chur/GR with 33.8 degrees, but this was only enough for second place in the statistics. It was hotter than ever in May, for example in Bad Ragaz/GR with 33.7 degrees or in Delémont/JU with 32.1 degrees. Measurements have been taken in Bad Ragaz since 1870 and in Delémont since 1959.
Legend:
May 20: hottest day in May 2022
May 20 was not only the hottest day in May 2022, but also a new May record for 12 official weather stations.
SRF
Records were also set for the number of summer days, especially in southern and western Switzerland. In Magadino/TI, an average of 7 days (1991-2021) in May are measured with at least 25 degrees. This year there were 17 summer days. The previous record was 14 summer days in 2017. A new May record was also broken in Geneva with 15 summer days. In Basel, on the other hand, the record was missed with 9 summer days. In May 2017 there were 17 days with at least 25 degrees.
Drought versus thunderstorms
In the second half of May, the summer heat also brought one or two heavy thunderstorms with heavy rain, squalls and hail. For example, on May 23, some strong thunderstorm cells developed, which together caused 22,000 lightning bolts and large-grain hail.
Legend:
hailstones
On May 23, some hailstones with a diameter of around 4 cm were reported.
Dominik leaves
In Lucerne, 30 mm of rain fell within 30 minutes and flooding ensued. However, thunderstorms only brought heavy rain in places. In May 2022 it was too dry in most places or even much too dry in the west. In French-speaking Switzerland, no more than 10 to 20 percent fell from the May norm (1991-2020).
Big snowmelt in the mountains
After the first third of May, the summer warmth came and the snow in the mountains felt it too. On May 9th there was 142 cm of snow on the Weissfluhjoch/GR (2536 m above sea level). On May 29, 27 cm were still measured. On average, the snow cover lost 6 cm per day and at the end of May was sometimes even below the minimum snow depth.
Legend:
Heavy snowmelt in May 2022
The white line represents the average snow depth. The blue line represents the snow depth for the current year. The sharp decrease in snow depth in May can be seen.
SRF