The first measurable snow in the lowlands falls on average at the end of November. In the low-lying areas of western and northwestern Switzerland, the snowpack does not start to form until the beginning of December. So far, the global warming of the last few decades has not yet resulted in the first measurable snow being delayed.
People often associate the actual start of winter with the first measurable snow (1 cm or more), when the landscape is covered in its first wintry white blanket. However, the first snowfall can occur much earlier without the snow settling and forming a snowpack.
The first measurable snow naturally falls later in the lowlands than at higher elevations. The central lowlands generally get their first blanket of snow in the last third of November, while in the lowlands of western and northwestern Switzerland this occurs around the first few days of December. According to measurements dating back to 1931, which are available in digital format (middle column of the table), the first snow in the lowlands of southern Switzerland is not generally seen until Christmas.The date of the first measurable snow depends to a large extent on the current weather situation and is therefore also somewhat random. In the lowlands of the northern Alps, the earliest dates recorded for first snow cover were in the last third of October (left hand column).
| Station | EARLIEST DATE OF FIRST SNOW | FIRST SNOW IN 30 % OF ALL YEARS | MIDDLE DATE OF FIRST SNOW | IN 30 % OF ALL YEARS FIRST SNOW AFTER | LATEST DATE OF FIRST SNOW |
|---|---|---|---|---|---|
| Genève | 26.10.1939 | 25.11. | 17.12. | 01.01 | 20.03.2008 |
| Neuchâtel | 26.10.1939 | 24.11. | 04.12. | 18.12. | 26.02.2020 |
| Basel | 23.10.2003 | 22.11. | 02.12. | 24.12. | 23.03.2008 |
| Bern | 25.10.1931 | 24.11. | 02.12. | 16.12. | 20.02.1993 |
| Zurich | 07.10.1936 | 20.11. | 28.11. | 06.12. | 11.02.1990 |
| Einsiedeln | 22.09.1931 | 29.10. | 08.11. | 16.11. | 20.12.1953 |
| Arosa | 03.08.1983 | 04.09. | 16.09. | 25.09. | 29.10.1953 |
| Lugano | 04.11.1974 | 14.12. | 27.12. | 10.01. | 04.03.2016 |
In years prior to 1931, the first measurable snow was observed much earlier. For example, on 28th September 1885, 9 cm of snow was recorded at the Zurich weather station (Annalen der Schweizerischen Meteorologischen Centralanstalt, 1885).
The measurement series available in digital format for all years since 1931 show large fluctuations from year to year in the date of the first snow cover. Given the general warming in recent decades, one might expect to see a trend towards the first measurable snow cover occurring increasingly later. However, no such trend is apparent from the original data.