ガイド
How to get the most from Snow Now
Everything you need to read a mountain forecast with confidence: how to use the site, what each weather model is, what every number on the page means, and how to check which model has been right.
4 steps to a forecast
24 weather models
3 views forecast, detail, history
1 check of who was right
On this page
Getting started
2ステップで予報
1. Location
Search for a ski resort, mountain or town, tap anywhere on the map, or use 現在地. Ski resorts and peaks come first in the search.
2. Elevation
Set the height you care about. Every forecast is corrected to it, because the air usually cools by about 6.5 °C for every 1,000 m you climb. Pick a ski resort and you get 山頂, 中腹 and 山麓 buttons. The forecast appears straight away, using the global model that does best in your part of the world; press 予報 to refresh it after a change.
Advanced settings
For the weather-wise. Once your forecast is showing, tap Advanced settings next to the place name. Full detail shows many models side by side. ここで最も正確 picks the models that have matched the nearest weather station best; 自分で選ぶ uses the models you tick further down the same page, where you also choose the data shown, units and table step.
Three ways to look at it
Forecast, Full detail and Snow history
- 予報 One model, laid out simply: weather symbols for each part of the day, then charts of snow and rain hour by hour, temperature, wind and the freezing level (with the resort’s top, middle and bottom marked), under a running total chart. Hover or touch any chart to see that hour on all of them. Auto picks the model for the area: the Met Office in the UK and Ireland, ECMWF in Europe, GEM in Canada, GFS in the USA, ACCESS in Australia and New Zealand, and ECMWF elsewhere. Choose another model at the top, and tap 表示項目を選ぶ to add or remove rows.
- Full detail Many models side by side, hour by hour, with the average of all of them at the top. Use it to see how sure the forecast is: when the models agree, trust it more.
- 積雪の履歴 A normal year, week by week, from 15 years of past weather: when the snow usually comes, how much falls as snow rather than rain, and the freezing level through the winter. Ski resorts get top, middle and bottom lines.
- 期間 How far ahead to look, from 24 hours to 14 days. The first two or three days are the most reliable.
The map
The map and 3D view
- The weather layer The map loads the chosen weather for the area you can see by itself, and fills in more as you move or zoom, shaded by the height of the ground. Tap any spot for its numbers, then 予報 or Full detail.
- Snow total, Rain total, All precipitation How much falls over the period you choose (next 24 hours to 7 days, or the past 24 hours to 7 days).
- Temperature, Freezing level, Wind, Cloud Conditions at one moment. Drag the time slider under the map, or press Play.
- Radar (live) Rain and snow measured by weather radar, from RainViewer. The map opens on it. Press 再生 under the map to watch the last 2 hours move, or drag the slider to a time. It is a measurement, not a forecast, and some countries and remote mountains have no radar.
- 3D表示 Tilts the map to show the mountains with the weather draped over them. Drag to move, pinch to zoom, twist to turn, and use the panel on the right to tilt, turn, zoom and face north.
- スキー場 Every ski resort as a dot when you are zoomed out (hover or tap for its name), and as a label with its top and bottom height closer in. Tap one for its forecast.
- ゲレンデ Runs and lifts: green, blue, red and black in Europe; green, blue and black in North America, Australia and New Zealand.
- 山 Off until you switch it on: well-known summits as an orange triangle with their name and height once you zoom in. Tap one for the forecast at its summit.
- ライブカメラ Live cameras near you when you zoom in, with their height, a timelapse and full screen.
- レイヤー Switch things on and off, in four groups: Ski & hiking, Places, Snow & safety, and Weather & light. A small grey note says when a layer needs you to zoom in, only works in 3D, or only covers one region. Everything new starts switched off.
- ハイキングコース、山スキー、クロスカントリー 標識のあるハイキングルートと、山スキー・クロスカントリー・そりのルート（Waymarked Trails）。
- 山小屋と氷河 山小屋・避難小屋（タップで標高、ウェブサイト、予報）と氷河（OpenStreetMap）。拡大すると表示されます。
- 斜面の傾斜 Slopes of 30° and steeper in yellow, orange, red and purple. Most avalanches start on slopes this steep. Zoom in to see it.
- 雪崩の危険度（ベータ版） Today’s official danger level, 1 to 5, from each European avalanche service, in the 3D view. Tap an area for its level and a link to the full bulletin. It is only the headline level: always read the bulletin itself.
- 降雪ライン 地図の時刻での降雪ラインを青い線で表示し、その上の地面を薄く白くします。
- 日なたと日陰 地図の時刻で日なたの斜面と日陰の斜面を表示。時間スライダーを動かすと変化がわかります。
- 動く風 予報の風に乗って流れる小さな白い線。速い線ほど風が強いことを示します。
- 観測された積雪 気象観測所に表示する積雪深。観測所自身が過去36時間以内に測定した場合のみ。
- 凡例 地図の下の角にあるボタン。オンにしている項目の色と線を説明します。
- ベースマップ The background map: muted, bright, grey, street map or satellite. It doesn’t change the weather colours.
Reading the forecast
What the numbers mean
Snow and rain
- 雪（cm） Fresh snow expected at your height. It is worked out from the water that falls and the temperature: colder air makes lighter, deeper snow.
- 雨（mm） Water falling as rain at your height. 1 mm of rain is roughly 1 cm of snow had it been cold enough.
- 着氷性の雨 Rain falling into air below 0 °C, which turns to ice on contact. Dangerous on roads and slopes.
- Running total chart Snow (blue), rain (green) and freezing rain (red) added up over time. Hover or touch it for the totals at any moment.
Temperature and the snow line
- 0℃高度 The height where the air is 0 °C. Below it you get rain; above it, snow.
- 降雪ライン Usually a few hundred metres below the freezing level, because snow takes time to melt as it falls.
- 体感温度 What the temperature feels like on your skin, with the wind and humidity taken into account.
- Max and Min The highest and lowest temperature in each period, at your height.
風
- 風 The average speed, with an arrow showing where it blows to. The colour runs from blue (calm) to red (strong).
- 突風 最も強い短時間の突風。稜線や山頂では平均風速より重要です。
Everything else
- Weather symbol Sun, cloud, rain or snow for the period, worked out at your height.
- Humidity How much moistureはair、in %. Near 100% often means cloud or fogにあります。
- 雲量 How much of the sky is covered, in %.
- 気圧 Air pressure at sea level in hPa. Falling pressure usually means worsening weather.
The models
The weather models
A weather model is a computer simulation of the atmosphere, run by a national weather service several times a day. Each one starts from slightly different measurements and splits the world into a grid of squares: the smaller the squares (the detail), the better it sees mountains and valleys, but the shorter it usually looks ahead.
Tip: use a detailed local model for the next one or two days, and the global models (ECMWF especially) for further ahead. When the models disagree, the weather really is uncertain: plan for the range, not one number.
Detailed local models
Shown only where they cover your location. Best for the next day or two in the mountains.
| モデル | From | Detail | Looks ahead | Covers | Good for |
|---|---|---|---|---|---|
| MeteoSwiss ICON-CH1 | スイス | 1 km | about 1½ days | The Alps | The finest detail in the Alps: valleys, ridges and local snow showers |
| MeteoSwiss ICON-CH2 | スイス | 2 km | about 5 days | The Alps | Detailed Alpine forecasts a few days ahead |
| DWD ICON-D2 | ドイツ | 2 km | 2日間 | Central Europe and the Alps | Thunderstorms and short, heavy snow showers |
| GeoSphere AROME | オーストリア | 2.5 km | about 2½ days | The Alps and Austria | Austrian and eastern Alpine valleys |
| Météo-France AROME HD | フランス | 1.5 km | about 2 days | France, the Alps and Pyrenees | French Alps and Pyrenees, sudden storms |
| ItaliaMeteo ICON-2I | イタリア | 2 km | about 3 days | Italy and the southern Alps | Italian Alps, Dolomites and Apennines |
| UK Met Office 2 km | UK | 2 km | about 2 days | UK and Ireland | Scottish hills and UK coasts |
| MET Norway Nordic | ノルウェー | 1 km | about 2½ days | Scandinavia and the Baltic | Norwegian, Swedish and Finnish mountains and coasts |
| DWD ICON-EU | ドイツ | 7 km | 5日間 | ヨーロッパ | A good all-round European model |
| NOAA HRRR | 米国 | 3 km | 18 hours to 2 days | 米国 | Storms and snow bands in the next day or two |
| Canada HRDPS | カナダ | 2.5 km | 2日間 | Canada and northern USA | The Rockies and Coast Mountains |
| Canada RDPS | カナダ | 10 km | about 3½ days | 北米 | North American storms a few days ahead |
| JMA MSM | 日本 | 5 km | about 2–3 days | 日本 | Japanese sea-effect snow |
| KMA LDPS | 韓国 | 1.5 km | 2日間 | Korea | Korean mountains |
Global models
They cover the whole world and look further ahead, but with less detail, so they smooth out the mountains.
| モデル | From | Detail | Looks ahead | Good for |
|---|---|---|---|---|
| ECMWF IFS | ヨーロッパ | 25 km | 15日間 | Usually the most reliable model worldwide, especially 2–10 days ahead |
| ECMWF AIFS (AI) | ヨーロッパ | 25 km | 15日間 | An AI model trained on decades of weather; very good with the big picture |
| NOAA GFS | 米国 | 13 km | 16日間 | Popular and free worldwide; reliable for the next week |
| DWD ICON | ドイツ | 13 km | about 7 days | Strong in Europe, good detail for a global model |
| UK Met Office Global | UK | 10 km | about 7 days | One of the best global models, especially for the Atlantic |
| Canada GEM | カナダ | 15 km | 10日間 | Useful extra opinion, good in North America |
| Météo-France ARPEGE | フランス | 25 km | about 4 days | Extra European opinion |
| JMA GSM | 日本 | 55 km | about 11 days | Broad picture in Asia |
| BOM ACCESS-G | オーストラリア | 15 km | 10日間 | オーストラリアとニュージーランド |
| CMA GRAPES | 中国 | 15 km | 10日間 | アジア |
Average of all models: in Full detail, the top row averages every model you have chosen. Over time, the average is often closer than any single model.
Who was right?
The accuracy check
Snow Now compares what each model forecast one day ahead with what the nearest suitable weather station actually measured. The station is chosen for being close and at a similar height, and each forecast is worked out for the station’s own height, so it’s a fair test.
Each model gets an error score for temperature, wind and precipitation, compared with the average of all the models. The lowest score ranks first, and ここで最も正確 uses the winners.
How to use it
1. Tap Advanced settings next to the place name and choose ここで最も正確.
2. Pick 評価期間 and 評価対象.
3. Open Full detail and scroll to モデルの精度 for the scores.
- 評価期間 The past 7 or 30 days shows who is doing well in the current weather pattern; over the last year, or this time last year, shows who is reliable in general or in this season.
- 評価対象 What matters to you. Auto judges on snow and rain. You can choose wind, rain and snow, temperature or everything.
- 表示 Use the best model only, or the best 3 or 5. Using a few is usually safer than trusting one.
A model that scored well last week isn’t guaranteed to be right tomorrow, and a station can be sheltered or misread. Use the check as a guide to which models to trust a little more.
Saved spots and your account
Tap ☆ 地点を保存 next to a forecast’s name to keep it. In 保存した地点, tap ⌂ to make one your home: the site opens there. Without a home spot, it opens at the ski resort with the most snow forecast. Sign in with your email (no password) to keep your spots and settings on every device. Your saved spots also show as quick buttons under the search box.
Snow alerts: signed in, tap the bell next to a Mountains spot in Saved spots. Each tap raises the amount (10, 20, 30 or 50 cm in the next 3 days, then off). We check twice a day and email you when the forecast reaches it, at most once every 36 hours per spot. Every email has a link to turn the alert off.
On your phone’s home screen: on iPhone or iPad tap Share, then Add to Home Screen; on Android, choose Install app or Add to Home screen from the browser menu. Snow Now then opens full screen like an app.
Sharing a forecast
リンクをコピー makes a short link to exactly what you are looking at: the place, height, models and view. Send it to friends before a trip.
Questions
Frequently asked questions
Why is this different from the ski resort's own forecast?
Resorts often use one model, or a forecaster’s summary, for one height. Snow Now shows many models at the exact height you choose. Compare the models: if most agree with the resort, you can be fairly confident; if they don’t, the weather really is uncertain.
Which height should I choose?
The height you’ll be skiing or walking at. For a resort, use Top, Middle and Bottom to see how the snow line cuts through it. Snow can fall at the top while it rains in the village.
Why does the map look blocky when zoomed right out?
Far out, the map loads fewer points to save data, then fills in detail when you stop. Zoom in a little or pause a moment and it loads more.
Why is the snow history for Japan lower than I expected?
The past-weather data (ERA5) smooths out mountains and under-counts heavy snow blowing in off the sea, so the amounts read low there. The share falling as snow is still reliable, which is why the chart shows that.
Do I need an account?
No. Everything is free without one. Signing in only keeps your saved spots, home spot and settings on all your devices.
Why is Snow Now's snow different from other forecasts?
Weather models smooth out the mountains. Each square of a model has one average ground height, which can be 1,000 m or more below the peaks, and the model’s own snowfall figure is for that average height. So it often shows too little snow at the top of a resort and too much at the bottom. Snow Now takes each model’s rain and snow (as water) and its freezing level, and works out how much falls as snow at the height you choose, at about 10 cm of snow for every 10 mm of water. That is why the top, middle and bottom of a resort show different amounts, and why our totals can differ from apps that show the model’s own snowfall.
Is there a page for my ski resort?
Yes. Every ski area with at least 5 km of runs has its own page, listed by country on the Ski resorts page, and Where’s the snow? ranks the biggest ones by snow forecast over the next 3 and 7 days. These are forecasts, not measured snow depths.
The page says the weather service is busy. What do I do?
The free weather service limits how many requests anyone can make each minute. Wait a minute and try again. Loading a smaller area, or fewer models, uses less.
Ready?
Find your next powder day
Something unclear, or a forecast that looked wrong? Tell us and we’ll improve the guide.