In June of 2025 heat waves combined with limited winter snowpack set the stage for significant glacier loss, 3% of the volume of Swiss Glacier. This followed on the exceptional losses in 2022 and 2023.

This same story in playing out through June of 2026, which will lead to this being the fourth year in the last five with exceptional glacier mass balance loss. On Grosser Aletsch Glacier on June 11th the snow line on the glacier was at 2450 m. By June 24th it had risen to 2800 m and by June 25th 2850 m. This is similar to the rapid rise of 400 m observed on Argentiere Glacier, France.

Grosser Aletsch Glacier snow line on June 25, 2026 averages 2850 m in this Landsat image.

The snow line rose to a record high 3200 m in 2022, and reached in 3100 m in 2025. Will 2026 set a new record? The snow line is not as high as the same date in 2022, though within ~25 m, but higher than late June 2025.

Above the late June snow line on Grosser Aletsch Glacier in 2022 and 2025 in Sentinel images. These two years had extensive June heat waves after winters with low snowpack. At the end of summer the snow line had risen to 3200 m in 2022 and 3100 m in 2025.