Alpine glaciers hit record early melt date as heatwaves sweep Europe
Switzerland's glaciers lost their winter snow cover on June 29, 2026, marking the second-earliest Glacier Loss Day on record. Two consecutive heatwaves in June and July pushed temperatures above 40°C in parts of Europe, raising the freezing level to 4,500 meters. The rapid melt has increased risks of avalanches and slope instability, and imagery shows significant retreat of glaciers like Bossons in the Mont Blanc massif.
The 2026 Glacier Loss Day arrived just three days after the record set in 2022, a year when Alpine glaciers shed roughly 6 percent of their total mass. The June heatwaves lifted daytime freezing levels to 4,500 meters, and overnight refreezing at high altitudes was minimal, compounding the melt.
Snowpack during the 2025-26 winter ranked among the five lowest in three decades. With less reflective snow cover, darker older ice absorbed more solar radiation, accelerating losses. The Rhône Glacier alone thinned by over four meters during June and July, currently losing about ten centimeters daily.
The accelerated melt could create a short-term runoff surge that may ease central Europe's drought conditions, but the longer outlook is troubling. Roughly 2.5 million people depend on the Rhône River for drinking water, with millions more reliant on the agriculture it sustains. If glacier retreat continues as projected, water security across the catchment could deteriorate significantly, while heightened avalanche and slope-instability risks may threaten alpine communities and infrastructure.