A study published in Science Advances finds that the Alpine region and Central and Eastern Europe are particularly vulnerable. If global temperatures climb by 3°C above pre-industrial levels, the frequency of supercell storms on the northern side of the Alps could rise by as much as 50 per cent.
These violent systems are already responsible for some of the costliest weather damage in Europe, driving a sharp rise in insurance claims over the past decade.
What exactly is a supercell?
Unlike ordinary thunderstorms, supercells develop when several atmospheric conditions align: warm, humid air near the ground, cooler air aloft, and winds that change direction with height. This combination makes the atmosphere unstable and allows storm clouds to begin rotating — the signature feature of a supercell.
Most often forming in the summer months, they can unleash torrential rain, hurricane-force winds, giant hailstones, and even tornadoes. Though rare in Europe compared with the US, supercells account for a disproportionately large share of thunderstorm-related destruction.
In recent months, they have struck with devastating effect. In June, a storm over L'Hôpital-le-Grand in France's Loire region pelted the town with hailstones up to 6 cm wide, smashing cars and roofs. In August, another supercell ripped across Rimini and Ravenna in Italy, toppling trees, wrecking crops, and disrupting trains with winds close to 100 km/h.
Rising risks and mounting costs
Supercell thunderstorms are part of a broader category of severe convective storms — systems that also include long-lived windstorms and large hail events. Globally, these were the most expensive natural hazards in 2023, with insured losses reaching nearly €55 billion.
Researchers warn that even a modest increase in their frequency could have outsized economic and social consequences for Europe, given the region's dense infrastructure and vulnerable agriculture.
Tracking the storms of the future
Monitoring supercells across Europe has historically been difficult due to inconsistent national radar systems. To address this, scientists at the University of Bern's Mobiliar Lab for Natural Risks and the Oeschger Centre for Climate Change Research, working with ETH Zurich, developed a high-resolution computer model that simulates storm cells at an exceptionally fine scale.
The model highlights the Alps as a supercell hotspot. Today, the northern slopes of the mountain range experience around 38 supercells per season, while the southern side sees about 61. With 3°C of warming, the study projects storm numbers could increase by half in these areas — heightening risks for Switzerland, Austria, northern Italy, and southern Germany. By contrast, the Iberian Peninsula and parts of southwest France may see fewer such storms.
Across Europe as a whole, the researchers forecast an 11 per cent increase in supercell activity.
"These regional differences illustrate the diverse effects of climate change in Europe," said lead author Monika Feldmann of the University of Bern.
Preparing for a stormier future
The findings underline the urgent need for European governments to prepare for more extreme weather. Experts warn that infrastructure, farming, emergency services, and insurance systems all need to adapt to withstand the growing risks.
"Understanding the conditions that create these storms is the key to better preparedness," Feldmann said. "With climate change, we must expect supercells to become an increasingly serious threat."