Since 15 August nobody in the Alps has been skiing. Four glaciers stopped during the summer of 2026, and Zermatt explicitly suspended its operation rather than ending it: it will resume as soon as natural conditions allow.
Except that nobody says what those conditions are.
So we worked it out. Not from a weather app, but from the last time exactly this happened: in 2022 Zermatt stopped summer skiing in high summer and resumed it after about fifty days, on 20 September. The week before that is the benchmark against which any forecast today has to be measured.
What was actually enough in 2022
Show the figures as a table
| Day | Coldest | Warmest | Below freezing all day |
|---|---|---|---|
| 10 Sep | -7.6 °C | 0.0 °C | no |
| 11 Sep | -8.1 °C | 3.3 °C | no |
| 12 Sep | -5.3 °C | 6.2 °C | no |
| 13 Sep | -2.0 °C | 8.3 °C | no |
| 14 Sep | 0.2 °C | 5.5 °C | no |
| 15 Sep | -4.7 °C | 2.7 °C | no |
| 16 Sep | -6.3 °C | 0.2 °C | no |
| 17 Sep (2.9 cm of snow) | -11.5 °C | -5.8 °C | yes |
| 18 Sep | -11.2 °C | -3.2 °C | yes |
| 19 Sep | -9.2 °C | -2.5 °C | yes |
| 20 Sep (reopened) | -8.4 °C | -0.6 °C | yes |
| 21 Sep | -9.1 °C | 0.5 °C | no |
| 22 Sep | -8.2 °C | 1.2 °C | no |
The finding is sharper than we expected. Cold nights alone were not it: from 1 to 16 September 2022 the minimum temperature was below zero on fifteen of sixteen days, and the area still stayed shut.
It turned only once the days themselves stopped rising above freezing. On 17 September snow fell, the daily maximum was minus 5.8 degrees, and three more days of continuous frost followed. On the fourth, Zermatt opened.
Physically that makes sense. A firn piste holds when the snowpack freezes through, and not just at the surface. A cold night hardens the top few centimetres; they thaw again the next afternoon. Only when a day fails to thaw at all does the frost work its way downwards. That is what a groomable summer piste lives on.
What is due before mid-September
Show the figures as a table
| Day | Coldest | Warmest | Below freezing all day |
|---|---|---|---|
| 31 Aug | 0.9 °C | 3.1 °C | no |
| 1 Sep | 0.9 °C | 3.1 °C | no |
| 2 Sep | 0.1 °C | 5.5 °C | no |
| 3 Sep | 1.2 °C | 8.6 °C | no |
| 4 Sep | 5.0 °C | 10.5 °C | no |
| 5 Sep | 4.1 °C | 8.3 °C | no |
| 6 Sep | 4.0 °C | 8.7 °C | no |
| 7 Sep | 0.1 °C | 7.9 °C | no |
| 8 Sep | -2.2 °C | 7.2 °C | no |
| 9 Sep | -5.9 °C | 6.8 °C | no |
| 10 Sep | -5.4 °C | 4.8 °C | no |
| 11 Sep | -3.0 °C | 2.1 °C | no |
| 12 Sep | -6.9 °C | 2.8 °C | no |
| 13 Sep | -0.4 °C | 1.8 °C | no |
| 14 Sep | -5.2 °C | 0.6 °C | no |
| 15 Sep | -4.6 °C | 6.6 °C | no |
The first week is mild to warm, with a spike on 4 September when the freezing level climbs to 4,570 metres. After that the cold does arrive: eight frosty nights, the coldest at minus 6.9 degrees on 12 September.
And still the answer is no. Because the 2022 criterion is not the night but the day, and the warmest moment stays above zero on all sixteen days. The coldest day in the whole outlook, 14 September, gets close at plus 0.6 degrees and misses.
On top of that comes what was already missing during the cold spell in late August: snow. Over sixteen days the model gives 2.1 centimetres on the Theodul glacier. In 2022, 2.9 fell on the day of the turn alone.
The four areas side by side
The ranking is no surprise, but how clear-cut it is, is. Between Zermatt and the Stelvio lie 300 metres of altitude and four degrees on the coldest night.
| Area | Altitude | Frosty nights | Days entirely below zero | Fresh snow |
|---|---|---|---|---|
| Zermatt, Theodul glacier | 3,500 m | 8 of 16 | 0 | 2.1 cm |
| Saas-Fee, Fee glacier | 3,400 m | 7 of 16 | 0 | 10.5 cm |
| Hintertux glacier | 3,250 m | 3 of 16 | 0 | 0 cm |
| Stelvio, Gentili | 3,200 m | 2 of 16 | 0 | 0 cm |
The 10.5 centimetres for Saas-Fee are the one bright spot in the table, and they stand on shaky ground: in the model they fall entirely on a single day, 14 September, far beyond the reliable range.
What the weather does not decide
This is where the arithmetic stops, and that belongs in the piece too.
Zermatt suspended operations rather than ending them, and writes that they will resume immediately once natural conditions allow. But the same statement contains a second sentence that most reports leave out: the challenges of technically maintaining the transport installations are steadily increasing. Frost does not repair a lift. What helped in 2022, besides the cold, was that maintenance work continued during the closure and the installations were ready when the weather came.
Saas-Fee put it differently and more firmly: pistes and glacier infrastructure no longer meet the standards. That is not a sentence a cold week undoes. The next announced date there is winter operation from 1 November.
Hintertux is the only one of the four that did not stop because of the weather at all, but because of demand in high summer. For that area the temperature calculation is therefore only half the answer. The other half is a commercial one, and it turns by itself in autumn when the training teams come back.
The Stelvio sits lowest, gets the least frost and has the shortest season. In 2022 it reopened on the same day as Zermatt. This time it comes out worst in our figures.
The one number to watch
If you want to know whether anything is moving, you need neither a snow depth nor a press release. One question is enough:
Is there a day on which, even in the afternoon, it does not rise above zero at 3,500 metres?
If that day comes, and three more follow it, things get interesting. Until then, every report about snow in Zermatt is exactly that: a report about snow, not about skiing. We keep the status up to date on the resort pages for Zermatt and Saas-Fee as soon as anything changes.
And the most honest answer to the question in the title: very probably not before mid-September. What comes after that, nobody can say seriously today, because in 2022 it turned only in the third week of September, and no model reaches that far.
Where this calculation runs out
- After eight days it is no longer a forecast. For 9 September the outlook gives a freezing level of 4,570 metres and, at the same time, a minimum temperature of minus 5.9 degrees at 3,500 metres. Together those two are physically impossible. The freezing level is a field of the model grid; the temperature is scaled down to the altitude we specify, and at the edge of the forecast range the two drift apart. We therefore base the statement on the temperature and draw the dividing line into the chart.
- 2022 and 2026 come from two different systems. The 2022 values come from the ERA5 reanalysis, those for 2026 from the running forecast. The comparison shows the order of magnitude, not the second decimal place.
- None of these figures is measured. They are model values scaled to terrain height, not station data. For the question of whether a day sits above or below zero they are reliable enough. For pinning down half a degree they are not.
- We do not know the operators’ threshold. The four days of 2022 are what was enough last time, not a rule written down anywhere. Piste width, crevasse conditions, staffing, maintenance and demand all feed into the decision.
Read on: No summer skiing left in the Alps · The cold spell in numbers · Is 2026 worse than 2022? · Why 2022 was the collapse summer
Sources and method
- Archive data 2022: Open-Meteo, ERA5 reanalysis, 1 to 22 September 2022, altitude fixed at 3,500 m (Zermatt) and 3,200 m (Stelvio) respectively. Retrieved on 31 August 2026.
- Forecast data 2026: Open-Meteo, which combines the models of MeteoSwiss
and the German weather service, 31 August to 15 September 2026, altitudes
3,500, 3,400, 3,250 and 3,200 m. Retrieved on 31 August 2026. The query is in
the project as a script (
scripts/wetterausblick.mjs). - Reopening in 2022: report by schneehoehen.ch of 19 September 2022 quoting Zermatt Bergbahnen and the director of S.I.F.A.S. The lift company’s own press release is no longer available.
- Operator statements 2026: report on seilbahn.net of 5 August 2026 carrying the statement of Zermatt Bergbahnen, statement by Saastal Bergbahnen of 10 August 2026, statement by Zillertaler Gletscherbahnen of 26 July 2026.
- Announced winter dates: our own dataset (
src/data/saisonstart.json), as of 21 August 2026.
