Snowfall in meteorological spring, i.e. between March and May, is not uncommon, even in the low-lying areas to the north and south of the Alps. At some weather stations, the largest winter snow amounts ever measured have occurred in March.
After the meteorological winter at the end of February, measurable amounts of fresh snow (snow cover of 1 cm or more) regularly fall at stations to the north and south of the Alps. Sometimes, the amount of snow that falls can be huge.
A typical example was the weekend of 4th and 5th March 2006, when many places in northwestern, northern and northeastern Switzerland saw between 40 and 50+ cm of fresh snow fall. At several measurement sites, such as those in Basel, Delémont, Zurich and St. Gallen, the highest one-day total of fresh snow in the entire measurement series up to 2020 was recorded on that particular weekend.
This was not the first time massive snowfall events were observed in March. On 11th March 1931 in Bern, for example, there was a blanket of snow measuring 96 cm. This is the highest value in the entire measurement series.
Over the long term, the average number of days with fresh snow on the northern side of the Alps is two to three in March, and one to two in April. Snowfall is rare after the middle of April. The table below shows the dates with the last measurable fresh snowfall of the season. The original data from the period of 1931–2020 have been used.
| STATION | EARLIEST DATE OF LAST SNOW | IN 30% OF ALL YEARS LAST SNOW BEFORE | MIDDLE DATE OF THE LAST SNOW | IN 30% OF ALL YEARS LAST SNOW AFTER | LATEST DATE OF LAST SNOW |
|---|---|---|---|---|---|
| Genève | 29.11.2013 | 13.02. | 23.02. | 05.03. | 22.04.1986 |
| Neuchâtel | 29.11.2013 | 20.02. | 01.03. | 22.03. | 21.04.1938 |
| Basel | 21.11.2013 | 16.02. | 10.03. | 25.03. | 27.04.1985 |
| Bern | 09.01.1997 | 02.03. | 15.03. | 01.04. | 04.05.2019 |
| Zurich | 12.12.2019 | 23.03. | 29.03. | 07.04. | 28.05.1961 |
| Einsiedeln | 02.03.1946 | 04.04. | 12.04. | 23.04. | 01.06.1962 |
| Arosa | 30.04.1992/1964 | 26.05. | 09.06. | 24.06. | 25.07.1977 |
| Lugano | 13.12.2019 | 12.01. | 30.01. | 07.02. | 14.04.1962 |
The measurement series available in digital format for all years since 1931 show large fluctuations from year to year in the date of the last fresh snowfall. Due to the general warming in recent decades, one might expect to see a general trend towards the last fresh snowfall occurring earlier and earlier. There are indeed measurement series that display such a trend, like that of Einsiedeln, for example. Other measurement series, however, such as Basel or Neuchâtel, show no trend whatsoever when it comes to the date of the last fresh snowfall.