4Kasta’s scorecard Updated 2026-11-08
Every call checked.
Misses included.
A forecast is only as good as its track record, so we publish ours. 4Kasta is the model behind every Bluepow call. Every number here is checked against what really happened: sunshine measured by weather stations and by satellite, and new snow measured at high-altitude snow stations.
- 1,032 resorts forecast
- 1,032 resorts checked by satellite
- 784 resorts checked for powder
Testing on five past winters (2021/22 to 2025/26). Live results replace these as this winter's forecasts are verified. Each winter was forecast by a model that had not seen it. Bluebird is checked against weather-station sunshine at 321 resorts, powder against high-altitude snow stations and Météo-France snow simulations, at 784 resorts.
Download the dataHow far ahead you can trust us
Share of our calls that came true, by days ahead. The amber line shows how often it happens anyway at that resort and time of year, which is what you would get by picking a random day. Bluebird is checked against weather stations at 321 resorts, powder against high-altitude snow stations and Météo-France snow simulations at 784 resorts.
Bluebird
Sunny, cloud-free ski day
Powder 10 cm+
10 cm or more of new snow overnight
Better than ECMWF on its own
ECMWF is the European forecast model, and one of the models Bluepow blends. To check that blending helps, we scored ECMWF on its own, tuned to each resort in the same way, on exactly the same 281,202 resort-days.
ECMWF is one of the models Bluepow blends, and it does not endorse Bluepow. Results from testing on past winters (2021/22 to 2025/26), same-day bluebird forecasts only, checked against station sunshine at 321 resorts. We haven't yet run this comparison for powder or for forecasts days ahead.
Same-day bluebird forecasts
281,202 resort-days, same days for both
Calls that came true
Real bluebird days forecast
Across the Alps
Same-day forecasts by country. Bluebird is checked against weather stations, powder against high-altitude snow stations and Météo-France snow simulations. Each country is compared with how often it happens there.
Bluebird calls that came true
Powder 10 cm+ calls that came true
Checked at every resort, by satellite
Weather stations sit near 321 of our resorts. To check the rest, we also compare our same-day bluebird calls with sunshine measured by satellite at all 1,032 resorts. We keep these figures separate from the station figures above.
Same-day bluebird calls that came true, checked by satellite
Satellite sunshine: © EUMETSAT. Testing on five past winters, same-day forecasts only.
Every number
The full results behind the charts, for each day ahead.
| Days ahead | Bluebird came true | Bluebird days forecast | Powder came true | Powder days forecast | Big powder (20 cm+) came true | Big powder days forecast | Based on |
|---|---|---|---|---|---|---|---|
| Same day | 79% | 86% | 56% | 65% | 49% | 44% | 281,202 resort-days (bluebird), 610,119 (powder) |
| Day 1 | 76% | 83% | 51% | 63% | 39% | 47% | 278,240 resort-days (bluebird), 694,412 (powder) |
| Day 2 | 74% | 82% | 51% | 63% | 38% | 46% | 276,691 resort-days (bluebird), 690,652 (powder) |
| Day 3 | 71% | 81% | 50% | 58% | 37% | 44% | 275,142 resort-days (bluebird), 686,888 (powder) |
| Day 4 | 67% | 78% | 45% | 57% | 35% | 39% | 273,593 resort-days (bluebird), 683,132 (powder) |
| Day 5 | 63% | 75% | 40% | 50% | 28% | 35% | 272,044 resort-days (bluebird), 679,366 (powder) |
| Random day | 30% | – | 5% | – | 1.5% | – | How often the event happens at that resort and time of year |
Honest about
what we miss.
What we haven't proven yet
The limits of these numbers, in plain words.
- Days 1 to 5 are scored for the evening forecast (issued around 18:00 UTC, the one behind the evening alert). The morning update, issued around 07:00 UTC, scores up to 3 points lower at each range. Same-day figures come from the morning forecast.
- Bluebird is checked against weather stations at 321 resorts. Satellite sunshine checks all 1,032 resorts, but so far only for same-day forecasts.
- In France, powder is checked against Météo-France snow simulations for each mountain range at mid-mountain height. These are a model, not measurements.
- Stations and satellite pixels measure one spot. Sun at the base can differ from sun at the top.
- Big powder days (20 cm+) are rare, about 1.5% of days, so those figures are less certain.
- Forecasts more than 5 days ahead are not scored, and we don't make them.