On Friday 4 September somebody in the Alps will be skiing again. S.I.F.A.S. is resuming operations on the Stelvio pass, from 06:30 to 12:00, and on its website gives the reason as the fallen temperatures.
That ends, after twenty days, the first spell in the Alps with no summer skiing at all.
And it means we were wrong.
What we wrote four days ago
On 31 August we worked out what was enough in 2022 for Zermatt to resume summer skiing, and ranked the four areas by it. About the Stelvio we wrote:
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.
It still comes out worst in our figures. It is reopening first anyway. If you publish a ranking and get overtaken from last place four days later, you owe your readers an explanation.
The forecast was right, the conclusion drawn from it was not
The easy move would be to blame the weather model. That does not work, because the model was right. What we predicted for the Stelvio on 31 August, against what the model says today for the same days:
| Day | predicted on 31 Aug | as of 2 Sep | difference |
|---|---|---|---|
| 1 September | 1.3 to 8.4 °C | 1.2 to 8.2 °C | 0.2 |
| 2 September | 1.5 to 9.0 °C | 1.6 to 9.5 °C | 0.5 |
| 3 September | 1.3 to 10.6 °C | 2.0 to 10.0 °C | 0.7 |
| 4 September | 5.3 to 14.9 °C | 5.0 to 14.9 °C | 0.3 |
The forecast was off by four tenths of a degree on average. What was wrong was not the number but what we concluded from it.
From the Zermatt case of 2022 we derived a criterion: four consecutive days on which it never rises above zero. That was the condition under which Zermatt reopened back then. We turned it into a general rule, and that was the mistake. It was Zermatt’s solution, not the only one.
What Friday actually holds
Show the figures as a table
| Day | Coldest | Warmest | Below freezing all day |
|---|---|---|---|
| 28 Aug | 4.1 °C | 7.7 °C | no |
| 29 Aug | 2.3 °C | 9.2 °C | no |
| 30 Aug | 2.8 °C | 10.8 °C | no |
| 31 Aug | 3.1 °C | 10.1 °C | no |
| 1 Sep | 1.2 °C | 8.2 °C | no |
| 2 Sep | 1.6 °C | 9.5 °C | no |
| 3 Sep | 2.0 °C | 10.0 °C | no |
| 4 Sep (reopens) | 5.0 °C | 14.9 °C | no |
| 5 Sep | 6.9 °C | 12.5 °C | no |
| 6 Sep | 6.7 °C | 14.9 °C | no |
| 7 Sep | 6.5 °C | 13.6 °C | no |
| 8 Sep | 5.3 °C | 11.5 °C | no |
| 9 Sep | 3.7 °C | 11.6 °C | no |
On 4 September the freezing level above the Stelvio climbs to 4,360 metres. The minimum temperature at terrain height is plus 5 degrees, the maximum 14.9 degrees. Fresh snow: none, and none anywhere in the series.
This is not an artefact of setting the terrain altitude too low. At 3,450 metres, the top station, the model still reports plus 3.4 to plus 13.3 degrees for the same day. Nothing on that mountain freezes that day.
The answer is in the opening hours
06:30 to 12:00. Five and a half hours, then it stops.
That is not a footnote, it is the answer. A firn piste does not strictly need a day that stays below freezing. It needs a state in the morning that holds until midday. Open at half past six and close at twelve, and you are using exactly what the night left behind, stopping before the sun undoes it.
In 2022 Zermatt took the other route: wait until the whole day sits in frost, then run normally. Both are valid answers to the same problem, and we mistook one of them for the law.
That the operator is not overstating its case shows if you look backwards rather than forwards. Temperatures did fall, just earlier: the daily maximum dropped from 30 August (10.8 degrees) to 1 September (8.2 degrees). The decision looks at the days just gone, our chart looks at the days ahead. Both are correct, and Friday lunchtime will still be warm.
What this means for the rest
Zermatt has, as of today, 2 September, announced no resumption. The Matterhorn Glacier Paradise sector remains closed. The lift company had written that operations would resume immediately once natural conditions allowed, and that it was reassessing daily. On the Theodul glacier frosty nights are indeed due from 8 September, down to minus 6.9 degrees. What is still missing there is snow: 2.1 centimetres over sixteen days.
Saas-Fee did not suspend its summer operation but ended it, on the grounds that pistes and glacier infrastructure no longer meet the standards. The next announced date there is winter operation from 1 November.
Hintertux stopped for commercial reasons rather than weather. For the autumn, more speaks for it there than the thermometer: when the training groups come back, so does the reason that was missing in high summer.
The Val Senales glacier has the second date, and this one is confirmed: from 19 September the glacier piste and its lift open in the Alpin Arena Schnals. Vinschgau Marketing told us so in writing on 1 September, in reply to our enquiry.
One subordinate clause in that reply explains the whole month: “numerous international ski teams will then be preparing for the coming race season in Schnals”. Autumn operation on the glaciers runs first and foremost on training groups, not on holidaymakers. It is also a plausible reading of the Stelvio’s morning window: whoever is in the gondola at half past six is rarely on a ski holiday.
And it closes the circle back to Hintertux. In July the Zillertal lift company named absent demand as its reason, noting that the training teams were on their summer break. Those are exactly the teams now coming back.
What we take from this
Our calculation of 31 August stands in what it measured: nothing freezes on the Stelvio, no snow falls, and the area is a long way from a state like Zermatt’s in 2022. What was wrong was the step from a measurement to predicting a business decision.
A ski area does not open when a threshold is met. It opens when somebody decides it is worth it, and that somebody knows their own firn better than any model does. So we will stick to the figures and keep writing down what they cannot do.
If you go up on Friday, take the opening hours seriously. At half past six the piste is in the condition it was opened for. At twelve it is not, and that is why it closes at twelve.
Read on: When can the glaciers reopen? · No summer skiing left in the Alps · The Stelvio is the last to stop · Stelvio resort page
Sources and method
- Reopening: notice by S.I.F.A.S. S.p.A. on passostelvio.eu, retrieved on 2 September 2026: “Due to the fallen temperatures the lifts will reopen on Friday 4 September from 06:30 to 12:00.” The site loads its notices only in the browser, so an automated fetch returns nothing; the basis is the page as displayed.
- Weather data: Open-Meteo, which combines the models of MeteoSwiss and the German weather service. 28 August to 9 September 2026, altitude fixed at 3,200 m, cross-checked at 3,450 m. Retrieved on 2 September 2026. Values up to and including 2 September have happened, the rest is forecast.
- Comparison with our own forecast: retrieved on 31 August 2026, documented in the article of that date.
- Zermatt: status of the lifts overview on matterhornparadise.ch on 2 September 2026, no notice of a resumption.
- Val Senales: written reply from Vinschgau Marketing of 1 September 2026 to our enquiry: “From 19.09.2026 the glacier piste and its lift will open there.” Translated from the German original.
