10 graphs showing how the climate in Switzerland has changed

Philip Rijk

Reto Fehr

We are heading for the warmest winter since records began and February is also on track for record high temperatures and low precipitation north of the Alps. Time to look back at the development of the climate in Switzerland over almost 100 years (some statistics only start in 1959).

But wait: is this climate or weather? The Federal Statistical Office (BFS), which can be experienced every day, describes the climate and weather patterns of a region over an extended period of time. The climate, like the weather, has always changed. However, according to the current state of research, in addition to natural factors such as the variability of solar radiation or volcanic eruptions, human influence is also increasingly noticeable.”

The BFS recently updated several climate data with values ​​for 2023. Here we show you ten of the most exciting topics.

The annual duration of sunshine is increasing slightly again at the selected measuring stations, after a small intermediate low around 1980.

Above-average average annual temperatures have been measured in Switzerland since the early 1990s: the eight warmest years since measurements began in 1864 were all recorded after 2010, with 2022 being the warmest year to date. The temperature increase was stronger north of the Alps than in the south.

Days when the maximum temperature exceeds 25 degrees are becoming increasingly common at all thirteen evaluated measuring stations. Even in Samedan, at 1700 meters above sea level, 13 summer days were recorded in 2023 and there is hardly a year without a summer day. Other regions have about 100 summer days per year, about 60 years ago there were between 50 and 60. On the Säntis (2500m) a summer day has never been recorded.

The Federal Statistical Office writes: “Warm days are days with maximum temperatures of 30° C and more. Depending on altitude, land cover, proximity to a body of water, etc., such warm days occur more or less often. With the general trend towards higher temperatures, an increase in the number of warm days has also been observed in Switzerland in recent decades.

At the higher measuring stations, such as Davos, Samedan or Säntis, there has never been a warm day. However, there has also been an increase at other stations since the turn of the millennium.

Even rarer than warm days in this country are tropical nights: nights when the minimum air temperature is above 20 degrees. But warm nights have also been steadily increasing lately, this applies not only to the south, but also to cities such as Basel, Zurich and St. Gallen. No tropical night has been measured in Bern since 1959.

The amount of precipitation can vary greatly from year to year, as shown in the curves below. No clear trend is visible for the whole of Switzerland.

Precipitation has increased locally and seasonally, for example in northeastern Mittelland in winter. However, what has increased in recent years is heavy rainfall.

There is also no clear trend in the number of days of precipitation over the past 65 years. It is striking that of all measuring stations, it rains most often on the Säntis.

Something similar to precipitation occurs with fresh snow. There are years with more snow, followed by years with significantly less snow at the 13 selected measuring stations. In recent years, years with little fresh snow seem to have become more common. It certainly won’t stay there that long.

At 2,500 meters above sea level, the Säntis shows an overall decrease in the amount of new snow. In the new millennium, there was never more than 15 meters of fresh snow per year, while previously there was always more than 15 meters of snow in the course of a year – or even regularly in the 1960s.

If the temperature drops below 0°C at least once a day, this is called a frost day. Whether and how often such frost days occur depends on various factors, but mainly on the height above sea level.

In general, it can be said that the number of frost days in Switzerland has decreased in recent decades. In Ticino 65 years ago there were about 50 frost days, lately it has usually been less than 20.

Just as with frost days, the same applies to ice days, where the temperature may never rise above zero degrees. The trend is slowly decreasing at all selected measuring stations.

When it comes to ice, let’s take a quick look at the glaciers: Since 1960, Swiss glaciers have lost a total of almost half of their ice volume, which will amount to about 48 km by 2023.³ had been estimated. The decline was particularly significant over the past two years, with volume losses of more than 4 percent compared to previous years.