How to read a snowfall forecast before a ski trip
You open the forecast and see precipitation in millimetres, snow in centimetres and a freezing level somewhere below the lifts. Will there be fresh snow where you plan to ski? Start by checking the elevation and the forecast interval—not just the biggest number on the page.
Choose the height where you will actually be
A forecast for the centre of Chamonix is not the same as a forecast for a slope above it. On SnowReportMeteo, select the place and check its elevation before comparing temperatures and snowfall. The selected height is used in our altitude processing; it does not make the forecast a detailed simulation of an individual piste. For a ski day, look at the base and the higher slopes separately.
Fresh snow is not the depth already on the piste
Our forecast snow row estimates new snowfall during the interval shown. It does not describe the existing snowpack. Yesterday's snow may have settled, melted or been moved by the wind; a groomed piste can also differ from undisturbed ground. Use recent resort reports and timestamped webcam images to assess existing cover. A seasonal photograph on a resort page is not a current snow report.
Read the water and snow values together
The precipitation row is in millimetres of water. Total model precipitation can include the water equivalent of snow, so it is not necessarily liquid rain alone. The centimetres in the snow row are a separate estimate derived from that precipitation and the forecast conditions. They are not extra precipitation to add to the millimetres. The example below shows how this looks in our own forecast table.
A real example: near Chamonix, at a selected elevation of 2,000 m
Archived forecast example, not current conditions. ECMWF model run: 18 October 2026, 12:00 UTC. Selected point: 45.9237°N, 6.8694°E; elevation: 2,000 m. Each row covers three hours. All times below are UTC (add two hours for Chamonix on these dates). Values are those displayed by our detailed forecast, including its rounding.
| Forecast interval (UTC) | Temperature at interval end (°C) | Total precipitation (mm) | Estimated fresh snow (cm) |
|---|---|---|---|
| 21/10 15:00–18:00 | -0.7 | 1.6 | 0.5 |
| 21/10 18:00–21:00 | -1.9 | 1.6 | 0.5 |
| 21/10 21:00–22/10 00:00 | -2.3 | 2.3 | 0.7 |
| 22/10 00:00–03:00 | -4.1 | 0.19 | 0.2 |
Open the latest forecast for this point
Download the dated example data
Why a small snow value can still be meaningful
In the final interval of our example, the displayed precipitation is 0.19 mm, the temperature is −4.1°C and the wind is westerly. Our current conversion uses a 10:1 snow-to-water depth ratio in these conditions: 0.19 × 10 ÷ 10 = 0.19 cm, displayed as 0.2 cm. The division by ten converts millimetres to centimetres. This explains the website's estimate; it is not a measurement or a universal physical ratio. Wetter snow, crystal structure and wind can produce different depths from the same amount of water.
The freezing level helps, but it is not a boundary painted on the mountain
The freezing level is an estimate of the height where the model air temperature reaches 0°C. Falling flakes can survive through some warmer air below it, and what reaches the ground also depends on the humidity and the layers it passes through. Do not treat a freezing level of 1,800 m as a guarantee of rain at 1,799 m and snow at 1,801 m. On our tables, a value with a less-than sign indicates a profile boundary rather than a precisely resolved freezing level.
Compare the same time window in both models
GFS stands for Global Forecast System, the American global forecast model. ECMWF stands for European Centre for Medium-Range Weather Forecasts, the organisation producing the European forecast used here. Compare their forecasts at the same location and elevation, over matching periods. A three-hour amount and a six-hour amount are not directly equivalent. Both of our tables use the same empirical fresh-snow conversion, so agreement in the snow row is not two independent checks of that conversion.
A practical check before you leave
Read the detailed intervals covering your journey and time on the slopes. Check whether most of the snow is forecast before you arrive or afterwards, then review wind, temperature and current camera images. Look again after the next model update, especially when temperatures are near freezing. In the longer outlook, follow the possible weather pattern rather than relying on an exact snowfall total. For lift openings, road access and avalanche conditions, use the resort's current information and the relevant official bulletins.
Sources and further reading
The dated example above comes from SnowReportMeteo. These official references explain the underlying weather concepts.