Where every number comes from

Every verdict on this site is generated from open data by a pipeline that runs each morning. Nothing is hand-written about current conditions, nothing is estimated by feel, and every value can be traced to a named source below. This page is the full recipe.

How are current conditions computed?

Each resort page combines four inputs, refreshed daily:

• Modelled snow depth and forecast - from the Open-Meteo weather API, queried at three elevations per resort: base, mid-mountain and summit. The headline depth is always the mid-mountain value, because that is where most of a ski day happens. Modelled values are labelled as modelled.
• Measured station depth - where a GeoSphere Austria weather station sits near the resort, we show its measured snow depth next to the modelled value as a reality check, named with the station and its elevation. Models drift; stations do not.
• Avalanche danger level - the official EAWS danger level for the resort's warning region, from avalanche.report in Austria and Italy and from the SLF in Switzerland, both members of the European Avalanche Warning Services. We display the level and link the bulletin; we never paraphrase avalanche advice. Where no bulletin covers a resort's region, or the bulletin has expired out of season, the page shows nothing rather than a guess.
• Season status - opening and closing dates from resort announcements, reviewed by a human each autumn. Dates estimated from historical patterns are explicitly flagged as estimated until the resort confirms.

How are the history statistics computed?

The snow-history chart on each resort page is built from the Open-Meteo historical reanalysis archive at the resort's mid-mountain elevation, covering the last 15 winters. For each half-month from November to May we compute three values:

• Reliability - the share of those winters with a snow base of 30 cm or more by that date (the 15th for the first half, the last day of the month for the second). 30 cm is a conservative threshold for a properly skiable groomed piste on typical Alpine terrain.
• Median depth - the depth on that date in the middle winter, not the average, so single freak seasons cannot flatter or slander a resort.
• Snowfall days - how often it actually snows in that half-month.

The statistics are recomputed every autumn with the most recent winter added and the oldest dropped, so the numbers track the current climate rather than a nostalgic average. Where a GeoSphere station exists, its long-term record is used to sanity-check the modelled history. Snowmaking is not modelled: real-world early-season coverage at well-equipped resorts is often better than the natural-snow statistics suggest, never worse, so the numbers err on the honest side.

When is the data updated, and what happens when a source fails?

The whole site is rebuilt daily at ~06:30 Alpine time (CET/CEST). Every verdict carries the timestamp of the data behind it. If an upstream source fails on a given morning, we keep the previous day's values and mark them stale - the page then says "updated" with the older date rather than pretending to be fresh. A verdict you read here is either today's data or honestly labelled as yesterday's; there is no third state.

What are the known limitations?

• Model vs reality. Modelled snow depth at a point elevation is an approximation of a whole mountain. The measured-station cross-check narrows the gap in Austria, where GeoSphere publishes station records we can read; Italian and Swiss coverage relies more heavily on the model.
• Piste conditions are more than depth. 40 cm of cold groomed snow skis better than 80 cm of rain crust. Depth and reliability are the best available proxies, not a full description.
• Season dates change. Resorts move opening dates with the snowpack. The daily rebuild picks up announced changes, but a date can be a few days stale in fast-moving early winter.

Data sources and licences

All sources are open data, used with attribution as their licences require:

Can you use our dataset?

Yes. The computed snow-history statistics (reliability percentages, median depths and snowfall days for every resort we cover) are published under CC BY 4.0 - cite SnowVerdict with a link. Journalists and researchers who want the underlying JSON files rather than the rendered pages can write to [email protected]. Derived statistics remain subject to the upstream licences listed above.