The location of record-breaking events in Switzerland is heavily dependent on the topography, as this is what dictates the spatial distribution of temperature, precipitation and wind.

Highest and lowest temperatures

Generally speaking, the higher the altitude of a location, the colder it is. The coldest place in the MeteoSwiss observation network is the Jungfraujoch, at 3,571 m above sea level and an average annual temperature of -6.7°C. In valleys and hollows, cold air pools can form, where the temperatures dip especially low. The coldest temperature ever recorded in Switzerland (-41.8°C) was in just such a location, at the weather station in La Brévine, recorded in the winter of 1987.

In the low-lying areas, temperatures are higher. Particularly high temperatures are recorded in the canton of Ticino due to its deep valleys and southern location. The warmest location in Switzerland is Lugano with an average annual temperature of 13.0°C. The highest temperature recorded in Switzerland was from the very hot summer of 2003 at the weather station in Grono (GR) at the southern opening to the Misox (41.5°C). With climate change, new record temperatures are becoming increasingly likely.

The table below provides an overview of the record temperatures in Switzerland and compares them to European and global records.

The data on the hottest and coldest year on record relates to the average temperature for that year. The lowest and highest temperatures ever recorded in the named regions are one-off occurrences.

Drought

Long dry spells are already having an impact on agriculture and forestry, as well as shipping and other industries. Due to the decreases in summer precipitation, and because evaporation is increasing due to climate change, the problem of drought in summer will continue to become more pressing in the future. In the driest areas of Switzerland, snow and glacier melt are important water sources. The receding of the glaciers and expected snow deficits will place additional challenges on these areas in the future.

Mountains and valleys not only play a major role in determining temperature, they are also central to the distribution of precipitation. With an average annual precipitation of 543 mm in the 1991-2020 period, the driest place in the MeteoSwiss observation network is Stalden-Ackersand in the dry Visper valley in the canton of Valais. This is around half the amount of precipitation that falls in a year in central Switzerland. The longest uninterrupted dry phase was recorded in Lugano in 1988, with 77 consecutive days without precipitation.

Switzerland is in a moderate climate zone, and much longer dry periods have been recorded in other parts of the world. In the Chilean city of Arica, there were 172 months without precipitation between the years 1903 and 1918.

Precipitation

The wettest place in the MeteoSwiss observation network is Säntis, which sees 2,840 mm of precipitation in an average year. When a large amount of water falls from the sky in a short space of time, this increases the risk for landslides and flooding in a local area. The largest amounts of precipitation falling within a short space of time are normally seen in Ticino, where the southern orographic effect is responsible for large amounts of precipitation. In central Switzerland, heavy precipitation is mainly caused by thunderstorms. For this reason, the heaviest downpours occur primarily in the summer months.

Because warmer air can retain more water, climate change is contributing to the fact that heavy precipitation events are increasing. Records are one-off events, however. This is true for all weather parameters, but particularly for precipitation. A record-breaking weather event needs various factors to come together (including the weather situation at the time of the occurrence, the region of Switzerland in question, and the changes in weather over several days or weeks preceding the event). This is why some of the record precipitation events happened a long way back in the 20th century, in spite of climate change.

The table below provides an overview of record precipitation values in Switzerland, and compares them to records seen in the rest of the world.

Snow

The weather situation is the deciding factor for record-high snow amounts. In the central and eastern Alps, the largest amounts of snow fall mostly in connection with northern orographic effects or north-westerly flow. In the southern part of the alps, it is the southern orographic effects that bring the largest amounts of snow. Similarly to precipitation, the largest snowfall amounts have fallen in the past in the higher-altitude locations. With snow, a distinction is made between snowfall (fresh snow amount) and snow cover (snow depth). The deepest snow depth was recorded in April 1999 on Säntis, with 816 cm.

The table below gives an overview of other snow-related records.

Wind and storms

In general, wind speeds tend to increase with altitude and distance from the earth’s surface. Close to the ground, the air circulation is slowed down by frictional forces. Particularly high wind speeds occur in Switzerland in deep depressions or in localised phenomena such as thunderstorms or foehn in the mountains. Due to the very localised character of thunderstorms, associated wind speeds are difficult to ascertain. Storms tend to occur in the winter months and can destroy large swathes of forest as well as infrastructure.

The highest wind speed recorded in Switzerland occurred in winter 1990 during storm Vivian, on the Great Saint Bernard pass. The table below gives an overview of the highest wind speeds recorded in Switzerland and the rest of the world.

No categorical prediction can be made regarding the effects of climate change on the future of winter storms with the currently available knowledge.