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- With global warming of 3 degrees Celsius, compared to pre-industrial times, summer precipitation in Switzerland is expected to decrease by 16 % (range from -27 % to +2 %) compared to the reference period 1991-2020.
- With global warming of 3 degrees Celsius, winter precipitation in Switzerland is expected to increase by 14 % (range from +8 % to +30 %) compared to the reference period 1991-2020.
- Future precipitation changes are likely to be more pronounced south of the Alps in both winter and summer than in other regions of Switzerland.
Understanding/planning for whether precipitation will fall in either form of rain or snow is of enormous importance for sectors such as water management, agriculture and forestry, energy, spatial planning and the management of natural hazards. Changes in the form, intensity and frequency of precipitation directly affects water availability, flood risk, agricultural and forestry yields, soil stability and ecological balance.
Further information on effects of climate change and mitigation measures taken by various sectors can be found on the website of the National Centre for Climate Services (NCCS).
Observed changes in mean precipitation
Since measurements began in 1864, annual precipitation amounts show little change over the entire period. Only on the north-eastern Swiss Plateau has there been an increase over the entire period, but this is mainly due to a period of low precipitation in winter, north of the Alps between 1880 and 1910. The trends observed since 1901 are not significant across Switzerland, or in any particular season. Although a slight decrease in summer precipitation has been observed since the 2000s, this could also be due to natural fluctuations.
Development of events with high precipitation levels due to warming is dealt with separately under "More intense precipitation."
Various regional patterns can be observed in the long-term precipitation measurement series. This is mainly due to the effect of the Alps acting as a climate barrier. As a result, Switzerland has a northern Alpine and a southern Alpine precipitation pattern. When precipitation trends for Switzerland as a whole are presented, significant regional differences are observed. One example can be seen in spring on the southern side of the Alps, where the period between 1975 and 1990 was significantly wetter than the decades before and after. This pattern does not exist on the northern side of the Alps.
Future changes in mean precipitation
Changes in seasonal precipitation
With increasing warming, average winter precipitation in Switzerland will continue to rise in future. In addition, precipitation during the cold season increasingly falls as rain rather than snow due to higher temperatures. Climate models show that the more the climate warms, the more likely and significant the decrease in summer precipitation will be. Uncertainties in the projections are significantly greater for summer precipitation than for winter precipitation. Since the summer months are currently wetter than the winter months in most parts of the country, the contrasting changes in summer and winter will lead to a flattening of the annual precipitation pattern.
The following changes in precipitation are expected in future:
- With global warming of 1.5 degrees Celsius compared to pre-industrial times – in a so-called “1.5-degree world” (GWL1.5) – a decrease in average summer precipitation of 7 % is expected, compared to the current reference period 1991-2020; while winter precipitation will increase by about 5 %. A 1.5-degree world is imminent.
- In a 3-degree world (GWL3.0), a more significant change is expected: Compared to the current reference period 1991-2020, summer precipitation will decrease by an average of 16 %, while winter precipitation will increase by 14 %.
| Change in mean precipitation in summer (%) | Change in mean precipitation in winter (%) | |
|---|---|---|
| 1961–1990 (central year 1975) | -2 | +5 |
| 1991-2020 (central year 2005) | 0 | 0 |
| Climate average 2024 | -8 [-19 to +3] | +7 [-9 to +24] |
| GWL1.5 | -7 [-20 to +5] | +11 [+4 to +20] |
| GWL 2.0 | -8 [-26 to +4] | +13 [+7 to +24] |
| GWL3.0 | -16 [-27 to +2] | +14 [+8 to +30] |
Tabular overview of the deviation of summer and winter precipitation (in %) in Switzerland compared to the reference period 1991–2020 for the WMO reference period 1961–1990, the current climate average 2024, and for a 1.5-degree world (GWL1,5), a 2-degree world (GWL2.0) and a 3-degree world (GWL3.0) Source: MeteoSwiss and ETH Zurich, Climate CH2025
Precipitation is subject to strong natural fluctuations, which is why the influence of climate change is less evident, relative/compared to the case of temperature. Rising temperatures increase evaporation and thus contribute significantly to more frequent and intense summer droughts. Effective climate mitigation measures can curb high levels of warming and thus also the decline in summer precipitation.
Regional changes in precipitation
Climate models show significant regional differences in expected changes in precipitation for higher warming levels (GWLs). In winter, the relative changes in seasonal precipitation are particularly pronounced south of the main Alpine arc. In summer, a widespread decrease in average precipitation is to be expected. In southern Switzerland and parts of western Switzerland, the expected decrease tends to be more pronounced than in other regions of Switzerland.
Changes in intensity, frequency and form of precipitation
It is not only changes in seasonal or annual precipitation amounts that are decisive, but also changes in the frequency, the intensity of individual events and in the form of precipitation. Heavy rainfall events are occurring more frequently and are more intense today than in the first half of the 20th Century. With climate change, Switzerland must expect a further increase in heavy rainfall across all seasons in the future.
Since the beginning of the 20th century, the zero-degree line in Switzerland has risen sharply in winter. At high altitudes, precipitation increasingly falls as rain rather than snow. As a result, snow cover is decreasing and the melting of snow and ice is accelerating. This trend will continue to intensify in the future.
