How will the winter of 2026/27 turn out?

El Niño keeps strengthening. In its diagnostic discussion of 8 October 2026, NOAA considers a strong to very strong El Niño likely through January to March 2027, with a chance remaining above 83 per cent. It puts the chance of an event exceeding every El Niño since 1950 (a three-month RONI of +2.5 °C or more) at 83 per cent for October to December and 70 per cent for November to January; in September it was 75 per cent for October to December. In the eastern equatorial Pacific, sea surface temperatures are locally more than 4 degrees above average.

One comparison needs care. NOAA reports the Niño 3.4 index at +2.1 °C for the past month, after +1.8 °C for August. The 90 per cent figure for a very strong event from September and the 83 per cent now given for strong to very strong are not the same quantity either, so they do not show a weakening. The one directly comparable number, the record chance for October to December, went up.

And it still says little about Alpine snow. A record event in the Pacific is a strong signal for North America and the tropics. For Europe the link is weak, indirect and runs through the North Atlantic Oscillation, which is not predictable months ahead. A stronger El Niño does not make that link stronger. It only makes the headlines louder.

39 of the 99 resorts in our overview have announced a starting date (85 in Switzerland plus the glacier ski areas of the Alps). The earliest was Schnalstaler Gletscher on 19 September 2026. All of the October openings have one thing in common: a glacier.

What that adds up to for the Alps: very little. The reasoning is in the next section, and at length in our article on the outlook.

The signal that governs Alpine snow is the North Atlantic Oscillation, the pressure difference between Iceland and the Azores. A positive NAO drives moist Atlantic air across Europe; a negative one lets high pressure sit over the Alps and dry them out. The difference between a good and a poor winter is largely this.

And the NAO cannot be forecast months ahead. Not because meteorology is not trying, but because it is a chaotic quantity whose predictability runs out after roughly two weeks. Anyone offering you an Alpine winter in August is either forecasting something else or forecasting nothing.

The Pacific signal that can be seen months ahead, El Niño, reaches Europe only heavily diluted. Statistical links exist, strong El Niño winters show a slight tendency towards a cold late winter in central Europe, but they are weak and unreliable. What El Niño does do reliably is raise the global temperature level, which in an already record-warm period raises the probability that precipitation falls as rain rather than snow at low altitude.

That is the honest state of it: altitude is the one variable you can check in advance. Everything else is watching and waiting.

How will the winter of 2026/27 turn out in Switzerland?

Nobody knows yet, and anyone claiming otherwise is guessing. What is known: El Niño is strong, NOAA puts the chance of a strong to very strong event through January to March 2027 at more than 83 per cent. For the Alps that says little, because the link runs through the North Atlantic Oscillation, which is not predictable months ahead. 39 of the 99 resorts in our overview (85 in Switzerland plus the glacier ski areas of the Alps) have announced an opening date; the earliest was Schnalstaler Gletscher on 19 September 2026.

Can an Alpine winter be forecast months in advance?

Not usefully. Seasonal models have real skill for North America and the tropics, where El Niño dominates. For the Alps the decisive factor is the North Atlantic Oscillation, and its behaviour is predictable a few days to at most two weeks ahead. Anything beyond that is a probability shift, not a forecast.

What does El Niño mean for snow in the Alps?

Less than the headlines suggest. A record event in the Pacific is a strong signal for North America and the tropics. For Europe the connection is weak and indirect, and a stronger El Niño does not make it stronger. It only makes the coverage louder.

When does it actually become clear how the winter will be?

In stages. Opening dates arrive from September to October, and they are statements of intent. The freezing level and the North Atlantic Oscillation become meaningful about a week ahead. The only figure that is not a forecast is the measured snow depth at the SLF stations, and that starts to matter from mid-November.