Science & Tech · Science & Environment · 7 hrs ago
Early snow after Swiss heatwave could raise alpine risks
After Switzerland’s record-hot summer of 2026, the timing of the first winter snowfall could affect mountain risks.
Snow falling on still-warm ground can stay wet underneath, and on smooth grass or rock the snowpack may suddenly slide as a glide avalanche.
An early, thick snow cover can also trap summer heat in permafrost above about 2,500 metres, contributing to ice loss and weaker slopes that may be more prone to rockfalls.
If the ground cools well before snow arrives, it can reduce some of the summer’s effects.
Warm streams and reservoirs can lower the efficiency of snowmaking, while depleted reservoirs may leave less water for making snow in January and February 2027.
At Weissfluhjoch above Davos, no snow fell from July to September for the first time in 90 years of measurements.
The first winter snowfall’s timing will therefore matter for avalanche danger, permafrost and preparations for the next ski season.
The timing of the first winter snowfall after Switzerland’s 2026 heatwave could affect avalanche danger and permafrost stability in mountain areas.
Early, heavy snow on warm ground can stay wet underneath and slide on smooth surfaces such as grass or rock slabs.
An early snow cover can also trap summer heat in the ground, adding stress to high-alpine permafrost.
Warm streams and reservoirs could reduce the efficiency of snowmaking, while dry reservoirs may limit water supplies later in winter.
At Weissfluhjoch above Davos, no snow fell from July to September for the first time in 90 years of measurements.
- Who
- Mountain communities and people exposed to alpine hazards. Experts at the WSL Institute for Snow and Avalanche Research described the risks.
- What
- Early snow after the 2026 heatwave could increase glide-snow avalanche danger and affect permafrost and snowmaking.
- When
- After the 2026 summer heatwave; possible water shortages for snowmaking are mentioned for January and February 2027.
- Where
- Swiss mountain regions, including high-altitude slopes and permafrost areas above about 2,500 metres.
- Why
- Early snow can insulate warm ground, leaving snow wet underneath and trapping heat in the ground.
This story does not have two clearly opposing sides.
No snow fell at Weissfluhjoch above Davos for the first time in 90 years of measurements.
The timing of the first winter snowfall is expected to affect avalanche, permafrost and snowmaking risks.
Dry reservoirs in lower-lying areas and mid-mountain regions could leave too little water to build new reserves for the following year.
- Weissfluhjoch
- 2,536 metres above sea level
- Snow-free period
- July to September 2026
- Measurement record
- First time in 90 years with no snow from July to September
- High-alpine permafrost
- Above about 2,500 metres
- Ideal air temperature for snowmaking
- Below minus 5 degrees Celsius
What people are saying
On smooth surfaces such as grass or rock slabs, the entire snow cover can suddenly slide off