Two people observe the effects of the drought on the Untersee, the smaller of the two lakes that together form Lake Constance, August 2022.
Keystone / Gian Ehrenzeller
Fifty years after the “drought of the century”, Switzerland is heading into summer with unusually low water reserves. Parts of the country are already under a drought warning. Drought can have unexpected effects, but simple measures can prevent critical situations.
“We’re not in the best position to face the warmest period of the year,” says Vincent Humphrey of the Federal Office of Meteorology and Climatology (MeteoSwiss). Fifty years after what’s remembered as “the drought of the century” in 1976, and following the scorching summers of 2003, 2015, 2018 and 2022, Switzerland could face another serious water deficit this year. April was among the driest on recordExternal link, and mountain reservoirs contain less water than usual.
Despite its many rivers, lakes and glaciers, Switzerland is not immune to drought. Climate change is increasing the intensity and duration of periods of water scarcity, with sometimes unforeseen impacts that go beyond dried-up rivers and yellowing meadows.
For example, drought can disrupt the supply of petroleum products that need to travel by waterway – something that, so far, not even the closure of the Strait of Hormuz has caused in Switzerland.
On May 21, the national drought monitoring system issued an alert for the Alps and the Central and Eastern Plateau. This is the second alert since the platform was launched just over a year ago.
“The trend from now until the end of June is worrying,” Humphrey warns. Without regular rainfall, the situation in Switzerland will become critical very quickly this summer, he says.
>> Extreme heat and drought are the main climate risks in Switzerland:
Switzerland exposed to drought risk in summer
Across much of Switzerland, river flow is low to very low for the season, MeteoSwiss notes. Below-average snowpack in the mountains is reducing the contribution from spring snowmelt, with effects on the main lowland rivers. The levels of several lakes, including Lake Constance and Lake Lucerne, are unusually low.
Groundwater levels also range from normal to very low across the country but are lowest in the Alps. In Graubünden, numerous measurement stations are recording levels below historical seasonal minimums.
Nationally, reservoir fill levels are currently at 13%External link, below the average of 20% for 2013–2021. “This could have an impact on hydropower production,” Humphrey says, adding that the situation is not yet that dire. “The level of artificial lakes is usually low at this time of year.”
Drought is a prolonged lack of water due to insufficient rainfall or heavy evaporation.
There are three types of droughts. Meteorological drought happens when there is no rain for a long time. In Switzerland, it means less than one millimetre of rain is measured at a station for the longest period.
Hydrological drought occurs when water levels in lakes and rivers drop below a certain point. Agricultural drought happens when the soil is very dry and plant roots do not get enough water.
Despite some rainfall, May has been drier than the long-term average. Forecasts for June indicate a trend towards dry weather, although with a high degree of uncertainty.
“My impression is that Switzerland is currently highly exposed to drought risk: two or three weeks without rain could be enough to create difficulties, especially in the presence of heatwaves,” Humphrey says.
However, he adds, regular rainfall during the summer, even if it is below average, could be sufficient to avert a severe drought situation.
Switzerland’s natural reservoirs are disappearing
In 2025, drought affected nearly one third of the Earth’s land surfaceExternal link. The cause is not just decreasing rainfall. A warmer atmosphere due to climate change accelerates evaporation from the soil and water loss from vegetation.
Drought is no longer confined to desert regions. It is spreading to temperate and densely populated areas as well. Parts of the Mediterranean, the United States and Australia have been dealing with persistent dry periods for years. By 2050, drought could affect three-quarters of the global populationExternal link and significantly reduce agricultural production.
Drought is an increasing challenge for Switzerland as well. Glaciers are retreating, and the snowpack at the end of winter is decreasing. “These natural reservoirs that used to compensate for the summer water deficit are disappearing,” Humphrey says. At the same time, water consumption for irrigating fields is rising.
Drought has become a relatively new phenomenon in some regions of Switzerland, which are not accustomed to managing water shortages or conflicts over water use, he adds, pointing to the Plateau, the Prealps and the Jura. Historically exposed regions of the country, such as the inner Alpine valleys and Ticino, are also affected, but they have more experience and infrastructure to cope with droughts.
Is Switzerland becoming drier?
According to an analysisExternal link by University College London and The Guardian, Switzerland is among the European countries that have recorded the greatest decline in groundwater reserves since the early 2000s. The study is based on satellite data that detect variations in the Earth’s gravitational field.
Kai Reusser, Swissinfo
Vincent Humphrey says he is familiar with the data. However, he believes that the map produced by The Guardian also takes the melting of Alpine glaciers into account. “This would explain why the decline appears so pronounced in Switzerland.”
Historical data from measurement stations in Switzerland do not show a widespread, long-term decrease in groundwater, he explains. “Nor is there evidence of excessive exploitation of aquifers.”
The unexpected impacts of drought on gasoline and livestock
Drought can have serious environmental, economic, and social repercussions. It causes severe damage to agriculture, reduces biodiversity, and increases the risk of forest fires.
Water shortages also negatively affect energy production, beyond just hydropower. When river flow decreases, water warms up more quickly, with possible consequences for nuclear power plants. In July 2025, the Beznau plant in northern Switzerland was temporarily shut down because of the high temperatures of the River Aare, which made it impossible to cool the reactors within environmental limits.
During the droughts of 2018 and 2022, Humphrey recalls, Switzerland had to draw on its strategic reserves of petroleum products. The level of the River Rhine had fallen to historic lows, hindering navigation and thus the river-based import of part of the gasoline, diesel and heating oil consumed in the country.
Drought can also significantly limit production of livestock feed. When importing it becomes too expensive, farmers are forced to cull part of their livestock herds. Humphrey notes that during the 1976 drought, an additional 25,000 animals were slaughtered in Switzerland.
During periods of drought, water is sometimes transported up into the mountains to ensure a supply for the mountain pastures, as seen here above the village of Sachsels in canton Obwalden in July 2022.
Keystone / Urs Flueeler
Priority for irrigation and water reserves to face wildfire
“Drought affects many sectors and vast areas: the combination of these effects is often underestimated,” Humphrey says. “People think each impact can be managed individually, but it’s their combination that creates the biggest problem.”
In Switzerland, there is no standardised national priority system for water use. Typically, municipalities and water operators define in advance the strategies and restrictions to be applied in the event of drought. Lower-priority uses are often those without economic or ecological value, such as washing cars, he explains.
“The idea is that it’s more useful for society to irrigate crops, supply public swimming pools or maintain wildfire reserves,” he says. Withdrawals from water courses are strictly regulated, and the law sets minimum residual flow requirements.
Drought management in Switzerland is a model for other countries
Switzerland has had a drought monitoring and warning systemExternal link since May 2025. The new platform combines meteorological, hydrological and satellite data. It provides up-to-date information on precipitation, river flows, and lake levels across all regions of the country.
“We also drew inspiration from what has been done abroad, for example in the Czech Republic, Slovakia and the United States,” explains Vincent Humphrey. Switzerland has in turn served as a model for other countries: it was the first to treat drought in the same way as other natural hazards such as storms, avalanches and forest fires.
“We also deliberately chose to take the risk of issuing drought warnings two weeks in advance,” says the meteorologist. The first was issued at the end of June 2025; it was withdrawn after rainfall in mid-July.
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Switzerland gets ready for increasing risks of severe drought
Simple measures to prepare for drought
The national warning “has encouraged many cantonal and municipal authorities to define or improve the protocols to be activated in the event of an alert”, Humphrey says. “This preparation makes it possible to respond more quickly and effectively.”
Last summer, officials raised the level of Lake Zurich in advance of dry weather by 5 centimetres (by adjusting the Letten dam along the River Limmat) because the system signalled a risk of drought in the following weeks. This simple measure helped increase available reserves.
By 2027, the drought alert system will be further refined, with the creation of a national soil moisture monitoring networkExternal link. In about 20 locations, sensors placed at different depths will measure water availability in the soil.
With the nation’s drought risk increasing, the warning system will make it possible to detect – and therefore manage – periods of water scarcity with greater precision.
Edited by Gabe Bullard/vdv/ts
