Intense, short-lived summer downpours across the Alps are set to become far more frequent and severe as temperatures rise due to climate change, scientists have warned. A new study by researchers from the University of Lausanne (UNIL) in Switzerland and the University of Padova in Italy suggests that a 2°C regional temperature increase could double the frequency of these dangerous rainstorms.
The Alpine region, warming faster than the global average, is especially vulnerable. In June 2018, Lausanne in Switzerland witnessed this risk firsthand when 41 millimeters of rain fell in just 10 minutes, flooding large parts of the city and causing damage estimated at 32 million Swiss Francs. Although such extreme events remain rare today, they are projected to become much more common as climate change intensifies.
“Our results show that an average temperature rise of just 1°C could already cause serious problems,” said Nadav Peleg, lead author and researcher at UNIL. “The sheer volume of water in such a short time overwhelms the soil’s ability to absorb it, triggering flash floods and debris flows that can damage infrastructure and threaten lives.”
To reach their conclusions, the research team analyzed data from nearly 300 weather stations across the European Alps—including Switzerland, Germany, Austria, France, and Italy—focusing on record-breaking short rainfall events between 1991 and 2020. Using these observations, they built a statistical model based on physical principles to predict how storm frequency would change under regional climate warming scenarios.
Their findings, published in npj Climate and Atmospheric Science, show that with a 2°C temperature rise, extreme storms currently expected once every 50 years could occur twice as often—once every 25 years. Even a 1°C rise, which could happen within decades, would bring a marked increase in the frequency and intensity of these events.
Francesco Marra, co-author and researcher at the University of Padova, emphasized that this risk is no longer theoretical. “We are already seeing signs that summer storms are intensifying,” he said. “This trend is expected to accelerate unless serious measures are taken.”
The study’s authors highlight the urgent need for adaptation strategies, such as improving urban drainage and flood defenses, to minimize damage and protect lives. As the Alpine region faces an increasingly volatile climate, proactive planning could help communities withstand the growing threat of flash floods and storm-related disasters.