Methodology
What we capture, when we capture it, where it comes from — and which numbers are observed, modelled or estimated.
When we check
We run a capture cycle four times a day, about every 6 hours. Each cycle reads the official lift, piste and snow status that a resort publishes itself, where it has a feed we can read, plus the weather model. Each resort shows its own capture time (“measured 06:14” or “reported today” when the source only gives a date). A resort without a direct official feed shows “not reported” — we do not fill the gap from another website. A source updates on its own schedule, so a change on the mountain shows at our next check after the source publishes it.
Where it comes from
- Lift, piste and snow status — only from the resort's own official status feed, for the resorts that have one. For every other resort the status is “not reported”: we do not use independent ski-information websites as a source of live status. A lift without a reported status is shown as “not reported”, not “closed”.
- Resort facts — totals (lifts, piste kilometres), elevations and planned season dates are static reference figures taken from a published ski-resort information website and shown with attribution. They are not a live status and are never used to say that a resort is open or closed.
- Lift and piste inventory — OpenSkiMap / OpenStreetMap data (ODbL) where the source doesn't publish one.
- Weather — the Open-Meteo weather model for each resort's coordinates.
- Holidays — public and school holiday calendars (OpenHolidays, Nager.Date), used only for the crowding estimate.
- Typical snow by week — ERA5-Land reanalysis (Copernicus Climate Change Service, CC BY 4.0).
The full registry with each source's licence is on Data sources.
Observed, modelled, estimated
Lifts open, pistes open and snow depth, as the resort's own feed reported them at our check, and the resort's planned season dates where they are published. Every value shows when it was checked. A dash (—) means it wasn't reported — never zero. A check that didn't succeed today is labelled "Not updated today" and yesterday's figures are not shown as today's.
Temperature, wind, freezing level and the weather forecast come from a weather model for the resort's coordinates — labelled "weather model", never "measured". Typical natural snow depth for a week of the season comes from the ERA5-Land reanalysis (Copernicus): a modelled reconstruction of past weather, not a snow measurement at the resort.
How busy a resort is (0–10) is a heuristic estimate from school and public holidays, the day of the week, the season and the weather, compared with the resort's uphill lift capacity. It is not live visitor data and not queue times, and its accuracy has not been measured yet. Anything marked ✦ is an estimate.
The trip-week forecast
Your week comes from our own forecasting model: it lines your dates up against the same weeks in past seasons and turns hundreds of past days into one clear score. Week scores are forecasts built from past seasons — estimates, not guarantees.
How we will measure forecast accuracy is described on Accuracy.
What we don't do
- We don't turn “not reported” into zero or “closed”.
- We don't show yesterday's check as today's.
- We don't show another resort's or a parent ski domain's figures as a village's own — a village page says the figures are for the whole domain.
- We don't publish ski pass prices without an approved price source.
- We don't show another website's older figures as a resort's current status.
On the day, always check the resort's own lift board before you ski. Questions: FAQ.