How our forecasts work

Where the data comes from

Every forecast on snowingplaces uses three weather models: the ECMWF IFS model from the European Centre for Medium-Range Weather Forecasts, the GFS model from the US National Oceanic and Atmospheric Administration (NOAA), and the ICON model from Germany's national weather service, the Deutscher Wetterdienst (DWD). We get all three through Open-Meteo.

For each place we ask each model for hourly snowfall, rain, air temperature, snow depth, wind and the freezing level. Forecasts are fetched and the whole site is rebuilt every three hours. The time of the forecast is shown at the top of every forecast page and in the footer.

Ski resorts get two forecasts

Weather on a mountain changes with height, so each ski resort has two forecasts: one at the height of its top lift and one at the height of the village or lowest lift. Both use the same coordinates, adjusted to each elevation. It is common for the village to get rain while the upper mountain gets snow, and the two forecasts show that. On maps and ranked lists, a resort is represented by its upper-mountain forecast.

What Likely and Possible mean

We count how many of the three models forecast snow, and say so:

• Likely (three dots): all three models forecast snow.
• Possible (two dots): two of the three models forecast snow, or the models disagree. It is worth checking again closer to the time.
• High confidence on a dry forecast: all three models agree there will be no meaningful snow.
• Medium confidence on a dry forecast: one model shows some snow and two do not.

For the next 24 hours, a model counts as forecasting snow when it shows at least 0.5 cm in total. For the next 7 days the threshold is 1 cm. For a single hour it is 0.1 cm. A place is only described as having snow on the way when at least two models pass the threshold.

Why snowfall is shown as a range

Amounts such as "10–20 cm" run from the lowest model's total to the highest model's total for that period. We do not average them into a single number, because a single number hides how much the models disagree. Ranges of 10 cm or more are rounded outwards to the nearest 5 cm. Totals under 1 cm are shown as "Under 1 cm".

Rain or snow

When temperatures are close to freezing, models often disagree about whether precipitation will fall as rain or snow. An hour is labelled "Rain or snow" when at least two models show snow and at least two show rain, or when one shows snow and another shows rain. We say so rather than guess.

Temperature, freezing level and wind

Temperatures are for the elevation of the forecast, so a resort's top-lift and village temperatures differ. Daily figures are the coldest and warmest hour of the day, averaged across the models. The freezing level is the height at which the air reaches 0 °C, and it comes from GFS and ICON only, because ECMWF does not publish it through our source. It is the quickest way to judge whether precipitation will fall as snow or rain at a given height.

Wind is the models' wind 10 metres above their own terrain, which is smoother and lower than real ridges. Expect stronger wind than shown on exposed upper lifts. Gusts are only mentioned when they reach 40 km/h (25 mph).

The 14-day outlook

Days 1 to 7 use all three models. ICON stops after about eight days, so days 8 to 14 use ECMWF and GFS only, and each day says how many of them show snow. At this range the models are useful for spotting a pattern, such as a cold, unsettled spell arriving, but the day and the amounts often move. We show it because people plan trips more than a week ahead, and we label it as an outlook so that nobody mistakes it for a forecast.

Units

Snowfall and depth are calculated in centimetres and shown with inches alongside. Temperatures are shown in °C and °F, wind in km/h and mph, and heights in metres and feet. Imperial figures are rounded, so they may not convert back exactly.

Will it settle?

For cities, we look at the average forecast air temperature during the hours when snow is falling. At −0.5 °C or colder we say it should settle. Between −0.5 °C and 1.5 °C we say it may not, and to expect slush. Above 1.5 °C we say it is unlikely to settle. This is a rule of thumb: ground temperature, how hard it snows and the time of day all matter too.

Snow on the ground

The snow depth we show is the middle value of the three models' estimates. It is a model estimate, not a measurement. A ski resort's own snow report is measured on its pistes, which are groomed and often topped up with snowmaking, so the two numbers can differ a lot. Use the resort's report for piste conditions.

When it usually snows: the snow record

The monthly chart on each place page shows the average number of days per month with at least 1 cm of snowfall, averaged over the ten years 2016 to 2025. It is calculated from ERA5, the global climate reanalysis produced by ECMWF for the Copernicus Climate Change Service, which we also access through Open-Meteo. For ski resorts the record is calculated at mid-mountain, halfway between the village and the top lift. For cities it is calculated at the city centre's elevation.

A reanalysis is a reconstruction of past weather on a grid, not a record from a weather station at that exact spot. It is consistent across the whole world, which makes places comparable, but it smooths out very local effects such as a single valley that catches more snow than its neighbours.

In season and out of season

Forecasts pause for places that are out of season. Glacier resorts are forecast all year. Other resorts are forecast from two months before their stated opening to two months after closing, or, where we have no dates, from September to June in the northern hemisphere and May to October in the southern hemisphere. Cities are forecast in the months when their snow record shows snow.

What a forecast cannot tell you

Global models work on grids several kilometres wide. They are good at the broad pattern, such as a storm arriving on Thursday, and weaker on exact amounts at one spot in steep terrain. Confidence drops quickly beyond about five days. None of this is a substitute for the local avalanche bulletin, the resort's own lift and piste report, or official weather warnings.