Temperatures have risen significantly in all regions of Switzerland since pre-industrial times, with the largest increases experienced in the winter months in central Switzerland, and in the summer months in the Alps. As far as precipitation is concerned, with the exception of an increase in central Switzerland, no significant changes have been observed.
Temperature and precipitation trends
MeteoSwiss has at its disposal long-term series of measurements of temperature and precipitation taken at several meteorological stations, dating as far back as 1864 (Swiss National Basic Climatological Network). These time series are extremely valuable for understanding climate change in the past and the present. Prior to analysis, the data are thoroughly checked for measurement errors and temporal homogeneity in order to ensure that any man-made factors such as the relocation of stations or installation of new instruments do not have an impact on the results (Quality Control/Homogenization). Using statistical methods, values can be derived from the measurements taken at the individual stations in Switzerland and applied to locations that do not have their own measurement stations. These gridded data indicate the spatial distribution and trends for temperature and precipitation in Switzerland. In addition, by collating all of the measurements taken throughout Switzerland, trends and changes can be presented for different parts of the country, or for the country as a whole.
Temperature change since 1864
The mean annual temperature in Switzerland has risen by around 2°C over the past 150 years, with the increase slightly lower south of the Alps than in the north of the country. Other than that, no significant differences in mean annual temperatures can be observed between the various regions.
When we look at the individual seasons separately, however, marked differences between the regions become apparent. While the lowlands of central Switzerland saw a steeper rise in temperatures than the mountainous regions in winter, the opposite scenario was true for the summer months. In spring and autumn, warming was more homogeneous across the different regions, with a greater degree of warming occurring in autumn than in spring in most areas.
Changes in precipitation volumes since 1864
Significant changes in precipitation volumes since 1864 are only evident in central Switzerland, where the change is primarily due to an increase in winter months. Springtime precipitation has also increased in the Lake Constance region. As far as all the other regions of Switzerland and other times of year are concerned, no significant changes in precipitation have been detected.
Temporal development of temperature and precipitation
The following application shows the trends in temperature and precipitation in Switzerland and certain sub-regions since systematic measurements began in 1864, or since pre-industrial times (pre-industrial reference period). The deviations of the annual and seasonal values from the average of the period from 1961-1990 (normal period) are illustrated.
Temperature trend since 1901
The graphic chart reveals the deviation of the annual temperature in all of Switzerland from the average of the period from 1961-1990. For example, the temperature was 0.7 °C lower than the average in 1980 and higher by 1.5 °C in 2000. The black line depicts the long-term trend starting in 1901 until present. Accordingly, the average temperature has risen by slightly more than 2.0 °C since the beginning of the 20th century.
With regard to the long-term temperature development, the seasonal patterns are very similar for autumn and winter. The temperature patterns of spring and summer are even more alike.
Characteristics of autumn and winter
- Between 1880 and 1890, winter temperatures were at an extremely low level, while autumn temperatures were likewise exceptionally low between 1880 and 1920.
- From 1900 to 1980, winter temperatures developed remarkably calmly without any long-term change being recorded. The same was also true for autumn temperatures between 1920 and 1980.
- In 1987/88, there was a sudden shift to a pronounced period of warm winters, although this trend has been muted somewhat over the past 15 years with a few cooler winters.
- No more extremely low autumn and winter temperatures were recorded toward the end of the 20th century.
Characteristics of spring and summer
- The 1940s were warmer than average.
- Temperatures held steady between 1960 and 1980.
- During the course of the 1980s, temperatures rose markedly and have since remained at a high level.
Different regional patterns can be observed in the series of precipitation measurements. This is due mainly to the fact that Switzerland has a contrasting northern Alpine and southern Alpine precipitation regime. The illustration of the precipitation development for all of Switzerland can mask considerable regional differences.
Long-term trends only in the north and during winter
- A significant increase in precipitation can be observed on the north side of the Alps during winter for the entire measuring period starting from 1864.
- The southern Alpine series of measurements for Lugano does not reveal a significant change in precipitation during winter.
- No significant change in precipitation is determined for the other seasons in all the regions of Switzerland.
Distinctive current precipitation developments
- A striking change toward drier conditions is observed in the south during spring after a phase of heavier precipitation around the 1980s.
- In recent years, greater amounts of precipitation have fallen during the northern Alpine spring.
- In winter, the amount of precipitation has decreased significantly at many measuring stations, especially in the Alpine region as well as in Switzerland’s west.
The data used for the temperature and precipitation diagrams is taken from measuring stations of the Swiss climatological network. In order to obtain an average for the whole of Switzerland or defined sub-regions, the measurement data from the individual stations is combined.
For temperature, the individual stations are weighted according to their level of representativeness. The methodology applied for determining the weightings is published separately and the data can be accessed on the MeteoSwiss website.
A simple average from the following stations is used for precipitation:
- All of Switzerland: Basel (BAS), Bern (BER), Château d'Oex (CHD), Chaumont (CHM), Davos (DAV), Engelberg (ENG), Geneva-Cointrin (GVE), Lugano (LUG), Säntis (SAE), Segl-Maria (SIA), Sion (SIO), Zurich / Fluntern (SMA).
- Northern Switzerland below 1,000 metres: Basel (BAS), Bern (BER) Geneva-Cointrin (GVE), Zurich / Fluntern (SMA).
- Northern Switzerland above 1,000 metres: no average available
- Southern Switzerland: Lugano (LUG).