A new Swiss snow file was set at Bortelsee station in the Simplon region in Switzerland, where 89 inches (226 centimeters) fell in just two days and 97 inches (247 centimeters) accumulated over three days. This unprecedented event, recorded from April 15 to 17, 2025, is now the largest amount of snow ever measured in short time in Switzerland, exceeding the previous 85 -inch records (215 centimeters) in two days at Bernina Pass in April 1999 and 90 inches (229 centimeters) in three days in Weissfluhjoch in February 1990.
The snowfall was mainly motivated by the “Hans” depression, a low pressure system that developed on the Gulf of Genoa. Appointed by Italian weather services, Hans channeled a strong southeast flow of the Mediterranean, carrying a warm air and loaded with humidity in the Southern Alps. As this mass of air has encountered the mountainous land, it was forced upwards, causing intense orographic precipitation on the southern slopes, especially in the Simplon region. The interaction between this wet air and the colder air masses at higher altitudes has led to large snowfalls, leading to record accumulations observed in Bortelsee.
The impact of this meteorological system has extended beyond snowfall records. Heavy snow has forced the closure of several major ski resorts, including Zermatt in Switzerland and Val d’Isère in France, due to an increased danger from the avalanche. Access to the rails and roads to these stations was temporarily cut and the electricity failures affected the Valais Upper parts. The authorities have issued avalanche warnings and weather alerts as the risk of avalanches, floods and landslides increased across the Alps.
