How the verdict works

A mountain excursion in Switzerland easily costs CHF 100 to 250 per person. Whether it's worth it depends almost entirely on one thing: can you see anything from the top? Peakobello answers that question for each summit, every day.

The forecast

We use the MeteoSwiss ICON-CH weather models, the high-resolution models the Swiss weather service runs for the Alps. ICON-CH1 has a grid of about 1 km and looks 33 hours ahead. ICON-CH2 has about 2 km and looks five days ahead. We query both for the exact summit position and altitude, plus a reference point in the valley below.

New model runs arrive every three to six hours. We refresh every three hours.

The score

For every hour between 09:00 and 17:00 we combine three things:

• Sunshine at the summit (50% of the score)
• Low cloud, the kind that wraps the summit (30%)
• Mid-level cloud that hides distant peaks (20%)

If more than 0.2 mm of rain or snow is forecast in an hour, that hour's score is halved. The day's score is the best run of 3 consecutive hours, so a clear morning still counts even if clouds build in the afternoon.

The verdict

• Go: 70 or more.
• Wait: 40 to 69.
• Skip: below 40.

Above the fog

In autumn and winter, the Swiss lowlands often sit under a lid of fog while the summits are in full sun. We flag those days when the valley reference point is grey and the summit is sunny. They're some of the best days to go up, and the forecast in town won't tell you.

Confidence

For today and tomorrow we compare the two MeteoSwiss models. If they agree within 15 points, confidence is high. If they differ by more than 30 points, or the day is four or more days out, confidence is low.

Is it running?

Under each verdict, one line says whether the way up is running. For today we ask the Swiss public timetable, which includes the mountain railways and cable cars, for trips to the top station. It knows season breaks and maintenance closures, but not a lift stopped on the day. Where the only way up is a cable car or chairlift, we also look at the forecast gusts at the summit: from about 70 km/h the lift may pause, from 100 km/h it will likely stop. Those wind lines, and every line for the days after today, are our estimate. Railways and funiculars keep running in wind, so they get no wind warning.

Chance of a clear summit

The score is our own index, so a 70 doesn't mean 70 %. To turn it into a real chance, we took a year of MeteoSwiss forecasts for the five summits with their own weather station (Jungfraujoch, Gornergrat, Titlis, Säntis and Pilatus) and checked each one against the sunshine actually measured there. A day counts as clear when the best three hours between 09:00 and 17:00 got at least 60 % sunshine. "70 % clear" means that on about 7 in 10 days with a forecast like this one, the summit was clear. We round to the nearest 10 % and never show more than 90 % or less than 10 %. For now the chance is shown for today only. Later days get one once enough of our own past forecasts for that many days ahead have been checked; we refit every week.

Panorama rating

The verdict says whether you'll see anything. The panorama rating says how much there is to see on a clear day. It's our own editorial judgement, not an operator claim:

• 5: high-alpine, with glaciers and four-thousand-metre peaks close up.
• 4: an Alpine summit with a wide view of the big ranges, from a little further away.
• 3: a pre-Alpine viewpoint over lakes and lowlands, with the high Alps on the horizon.

Ticket prices, ski areas and highlights come from each operator's own website. Where an operator only shows a "from" price, we say so.

How often we're right

Every morning we keep a copy of the forecast you saw. The next day we compare it with the sunshine MeteoSwiss actually measured at its weather stations on Jungfraujoch, Gornergrat, Titlis, Säntis, Pilatus, Moléson, Monte Generoso and Cardada and Cimetta.

• A Go counts as right when the hours we recommended got at least 60% of the possible sunshine.
• A Skip counts as right when no three hours in a row got even 35%.
• Wait days aren't scored: they mean "maybe".

The other summits have no weather station at the top, so they aren't checked yet.

What it can't do

Weather models can be wrong, especially about where exactly a cloud base sits. A forecast isn't a guarantee. Always check the live webcam (the "See it live" link on each summit) before you buy, and dress for the altitude.

Sources

Forecast data: MeteoSwiss, via Open-Meteo, licensed under CC BY 4.0. The verdicts are our own calculation and not an official MeteoSwiss product.