Severe weather outbreak brings giant hail, flash floods, and rare June blizzards to Europe
A Level 3 severe weather outbreak is sweeping across Europe with destructive hail, damaging winds, flash floods, and potential tornadoes impacting multiple countries on June 4, 2025.
Supercell over Lake Balaton, Hungary on June 3, 2025. Credit: huahinjoe
Iceland’s northern fjords, including Þverárfjall and Eyjafjörður, saw an unseasonal snowstorm with hurricane-force winds, creating blizzard conditions on Tuesday, June 3.
The Icelandic Meteorological Office reported heavy snow and near-zero visibility, with mountain passes like Fljót drifting over.
The National Commissioner of Police declared a public safety uncertainty phase, closing roads and stranding thousands as airlines and ferries cancelled departures. According to forecaster Birgir Höskuldsson, heavy snowfall at low elevations is forecast to persist through June 4.
In L’Hôpital-le-Grand, along the Loire River’s western bank in France, a supercell storm struck on June 3, producing hailstones 5–6 cm (2–2.3 inches) in diameter.
Residents described an “enfer blanc” (white hell) as hail piled up like a winter blanket, damaging vehicles, shattering windshields, and covering a horticultural greenhouse.
Tiles were torn from roofs, and more severe storms are expected with heavy rain and 80 km/h (50 mph) winds in eastern France on June 4. Parents sheltered children indoors as transport and power services were disrupted.
Northeastern Slovenia’s Goričko region, known as Europe’s ‘hail alley,’ was hit by a supercell thunderstorm on June 3, with hailstones larger than tennis balls (6–7 cm) striking Lucova, Šulinci, and Gornji Petrovci.
ARSO reported nearly every roof damaged, with skylights at a school shattered and crops flattened. Village officials used backhoes to clear hail, while a mayor requested aid to protect orchards. Fallen trees and burst drains overwhelmed relief teams, with recovery expected to take days.
Hungary experienced similar conditions with two powerful supercells sweeping in from the west and causing significant storms primarily in Western Transdanubia on June 3.
The storm first impacted the areas of Szentgotthárd and Körmend before striking hard along the Tapolca line, with ice larger than walnuts damaging trees, vegetable gardens, and agricultural fields, leaving roads littered with fallen leaves.
This prompted a second-level storm warning for Lake Balaton’s central and western basins, where swimming was prohibited due to hazardous conditions.
Rokycany in western Bohemia, Czech Republic, was inundated by flash floods after intense convective rain, as forecast by the Czech Hydrometeorological Institute on June 3.
Waterways burst their banks, flooding basements and streets, prompting a state of emergency. Firefighters evacuated elderly residents and pumped out homes, while Pilsen and Prague sent aid to displaced families. Sandbags were distributed to combat further inundation.
ESTOFEX’s forecast for June 4, issued on June 3, warns of a Level 3 risk across central Europe, including northeast Switzerland, southern Germany, and Czechia.
Analyst Christoph Tuschy highlights a rare overlap of MUCAPE values reaching 2000–3500 J/kg and deep-layer shear up to 30 m/s (100 ft/s), supporting long-lived supercells, damaging winds of 100–120 km/h (62–75 mph), hail over 5 cm (2 inches), and isolated strong tornadoes.
Surrounding areas, like southeast France, northern Austria, northwest Italy, and Poland are under Level 2, with slightly lower probabilities but similar hazards.
Forecast models show the potential for derechos (widespread, long-lived, straight-line winds), embedded supercells, and localized flash flooding in terrain-locked areas, especially in southeast Switzerland, where rainfall totals may exceed 200 mm (8 inches) in 6 hours on June 4.
Level 1 alerts extend farther into Sweden, Romania, eastern Ukraine, and parts of Russia. These regions may experience large hail, strong gusts, and isolated tornadoes, particularly in Sweden and western Russia, where low LCLs and strong low-level shear favor rotating storms despite low instability.
Reet is a science journalist and researcher with a keen focus on extreme weather, space phenomena, and climate-related issues. With a strong foundation in astronomy and a history of environmental activism, she approaches every story with a sharp scientific lens and a deep sense of purpose. Driven by a lifelong love for writing, and a curiosity about the universe, Reet brings urgency and insight to some of the most important scientific developments of our time.
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