Mountain Weather: Where to Find Official Forecasts and How to Read Them

Why the forecast for town tells you nothing about the pass

On your phone: full sun and 64 °F (18 °C) in town. The pass you’re aiming for is 6,600 feet higher, and that’s where you’ll spend the day. Temperature drops by an average of 0.65 °C every 100 meters, or about 3.6 °F every 1,000 feet, according to MeteoSwiss [1]: at 9,800 feet (3,000 m), that 64 °F becomes about 41 °F (5 °C), before you even factor in the wind. The app wasn’t wrong; it was just talking about town.

There are exceptions. In clear fall or winter weather, a temperature inversionA situation where temperature rises with elevation instead of falling, often under a sea of clouds or valley fog. can make the air milder at 8,200 feet (2,500 m) than on a valley floor at 1,600 feet (500 m) [2]. The UK’s Met Office sums up the problem: in the mountains, the weather can change dramatically from one hour to the next and from one hill to the next [3].

That’s what mountain forecasts are for. National weather services use them to give conditions where you’ll actually be hiking: wind on the ridges, temperature at 6,600 or 9,800 feet, how high the freeze reaches. Here’s where to find them in each country our editions cover, followed by what their terms mean, as the services themselves define them.

France: Météo-France’s mountain section and its Vigilance map

It all starts on Météo-France’s Météo Montagne page. It’s split into seven regions, from the Northern Alps to Corsica by way of the Pyrenees, the Jura, the Vosges, and the Massif Central, with forecasts by ski resort, snow cover, and snow depths [4]. Each region lists its forecast points, some of them high up: the Northern Alps page offers, for example, “Chamonix Mont-Blanc 3845m” and “La Plagne 3250m,” elevations given in meters [5].

Météo-France also describes a mountain safety bulletin, the Bulletin Sécurité Montagne, published every day at 5 p.m. for that day and the next, and for the day after that as well in the Alps, Corsica, and the Pyrenees. It’s written by département, a French administrative area, in those three regions, and by range in the Vosges, the Jura, and the Massif Central, with an elevation threshold above which it applies. It flags hazards that exceed a mountain-specific threshold, such as thunderstorms, heavy precipitation, high winds, cold, or fog, then gives precipitation, wind on the ridges or at a given elevation, with its gusts, and temperatures at reference elevations, including the 0 °C (32 °F) isotherm when it’s useful [6].

One caveat about the Bulletin Sécurité Montagne: the page that presents it, the one for the Vosges, sits in Météo-France’s “prototype workshop,” whose products are experimental and don’t replace its official output [8]. Its method is still a useful guide to reading any mountain forecast, and we’ll come back to it.

Switzerland, Austria, and Germany: three services and an Alpine club

Switzerland: MeteoSwiss

MeteoSwiss publishes hour-by-hour local forecasts along with their uncertainty: a curve for the median scenario and, around it, a band containing 80% of the calculated scenarios [9]. The wider the band, the less certain the forecast. Its warnings follow the five-level scale used by Switzerland’s federal natural hazards services, from green (“no or low danger”) to dark red (“very high danger”); the portal points out that levels for two different hazards can’t be compared directly [10].

Austria: GeoSphere Austria

In Austria, the national service is called GeoSphere Austria. On its forecast page, a menu lets you pick a state: the forecast text adjusts, including a Bergwetter, or mountain forecast, where one exists for that state [11]. Its warnings are “impact-based”: they factor in wind speed, rain, or snowfall, but also the season, the time of day, and whether the trees have leaves [12]. GeoSphere also runs an observatory on the summit of the Hoher Sonnblick, at 10,190 feet (3,106 m) [13].

Enlarge photo

Germany: the Deutscher Wetterdienst

The Deutscher Wetterdienst (DWD), Germany’s national weather service, publishes a forecast for southern Bavaria every day at 10:30 a.m., with temperatures at 6,600 and 9,800 feet (2,000 and 3,000 m) and the snow line [14]. Its warnings have four levels, yellow, orange, red, and violet, plus a hatched advance notice when a very dangerous event is shaping up but its area, timing, and intensity aren’t yet certain enough [15]. One detail matters in the mountains: on exposed summits, gust warnings are decided case by case [16].

The German Alpine Club’s Bergwetter

The German Alpine Club publishes a Bergwetter for 17 regions of the Alps, with headlines written by GeoSphere Austria meteorologists. Since May 2026, each region has a table in 6-hour blocks: temperatures at typical elevations, mean wind and gusts, snow line, 0 °C isotherm, and the likelihood of precipitation, thunderstorms, and fog on a scale of 0 to 3. Its values apply to open, exposed spots such as ridges and passes [17].

United Kingdom: the Met Office and MWIS

The UK’s national weather service, the Met Office, publishes mountain forecasts for 10 areas, from the Northwest Highlands of Scotland to the Brecon Beacons in Wales by way of England’s Lake District and Eryri, or Snowdonia [3]. They come out every afternoon before 6 p.m., cover the evening, then two days in detail and a three-day outlook, and are updated before 6 a.m. [18]

Each forecast opens with nine mountain-specific hazards, each rated with a nil, low, medium, or high likelihood, which apply at or above 1,000 feet (300 m); a mountain hazard can be in effect with no weather warning for the same area. Next comes a table of wind, gusts, temperature, and “feels like” temperature, from valley to summit, followed by a text written by a meteorologist [18]. The national warnings, yellow, amber, or red, combine the likelihood of the event with its expected impact [19].

United States: the National Weather Service point forecast

On weather.gov, the National Weather Service (NWS) gives you a map to click on the spot you’re heading for. The forecast you get covers a square roughly 3 miles (5 km) on a side around that point [22], and the page shows the elevation of the forecast point (“Elev.”): compare it with your objective, because it may be lower than the summit you have in mind.

NWS alerts use three words. A watch means a hazard is possible, a warning that it’s happening or imminent, and an advisory that it’s less severe than one calling for a warning. The thresholds aren’t national: each local NWS office sets its own criteria [23].

Isotherm, rain-snow line, freezing level: three elevations that get mixed up

The 0 °C isothermThe elevation at which the air temperature reaches 0 °C (32 °F): below it the temperature is above freezing, above it below freezing. separates air above freezing, lower down, from air below freezing, higher up. Météo-France describes it as an imaginary surface, usually fairly flat, that forecasters call the “iso 0” among themselves [24]. The one in forecasts isn’t the one on the ground: MeteoSwiss distinguishes the isotherm in the free atmosphere, measured by weather balloons, from the one derived from ground stations, and its forecasts give the former. Near the ground, temperature can vary a lot over a short distance, especially in the six winter months [25].

The rain-snow lineThe theoretical elevation at which as many snowflakes as raindrops are falling. MeteoSwiss also calls it the snowfall limit. sits lower, often 660 to 1,300 feet (200 to 400 m) below the 0 °C isotherm, according to both Météo-France and MeteoSwiss [26, 2]. Here’s a reminder that can save your evening: it isn’t the elevation where snow sticks to the ground, which is usually 160 to 660 feet (50 to 200 m) higher [26]. And in heavy precipitation, snow can fall much lower, as much as 2,600 feet (800 m) below the 0 °C isotherm, according to Météo-France [26].

Enlarge diagram

If you hike in Britain, watch out for a false friend. In Met Office mountain forecasts, the freezing level isn’t the air isotherm: it’s the level above which snow is expected to settle, or the ground to be frozen, without accounting for surfaces melting in direct sun during the day [18]. The National Weather Service uses the same term for the elevation where the air temperature first drops below freezing [27], in other words the 0 °C isotherm.

“30% chance of rain”: one number, several definitions

The chance of rain is the most-read number in any forecast, and one of the most misunderstood. None of the services cited here says it means rain 30% of the time, but they don’t all calculate it the same way. At MeteoSwiss, it’s a bit like asking ten neighbors: if three of them grab an umbrella, the forecast says 30%. The neighbors, here, are scenarios calculated by the models from slightly different starting conditions [9].

Two points hold whatever the service. In thunderstorm weather, calculated probabilities are lower than for widespread rain, because showers hit in patches, and if one does hit the forecast spot, the median amount given is often far too low, MeteoSwiss warns [9]. As for thunderstorms, the German Alpine Club keeps it simple: it’s a thunderstorm when you can hear thunder, and strong storms, with hail and damaging gusts, remain possible even when the likelihood is low or moderate [17].

Mean wind, gusts, summits in the clouds: the other words in the forecast

Mean wind is, by convention, an average over 10 minutes, measured 33 feet (10 m) above the ground. A gustA sudden jump in the instantaneous wind that exceeds the mean wind by more than 10 knots (about 12 mph), according to Météo-France. is stronger when the air is unstable, the mean wind is strong, or the terrain disrupts the airflow [24]. In mountain forecasts, wind is given at a set elevation or at ridge level [6]. The German Alpine Club points out that strong gusts can blow even when the mean wind stays moderate [17], and the Met Office that the strongest winds it forecasts are normally found on exposed peaks and ridges [18].

British forecasts add a section that hikers tend to read first: the chance of cloud-free tops, or, as the Met Office puts it, the chance of your efforts being rewarded with a view from the summit, with the extent and persistence of low clouds across the area [18]. MWIS gives it as a percentage [21]. There’s more at stake than the photo: the Met Office lists poor visibility among its mountain hazards, with low clouds or snow often cutting visibility to 160 feet (50 m) or less [18].

Reading a forecast without asking it to decide for you

A forecast describes the expected weather over an area; it doesn’t tell you whether your hike is a go. Météo-France spells it out: its mountain bulletin provides neither a risk assessment for any given activity nor advice, and it’s up to each user to assess the risk based on their activity, exposure, experience, and gear, then decide whether to go ahead, adjust, or call it off [6].

A few habits help. Check the date and time of issue, since a forecast can be amended before the next scheduled one [6]. Note the area and the elevation it covers: actual conditions can differ sharply from the regional forecast on steep ground, in valleys, or in very exposed spots, the German Alpine Club reminds readers [17]. And don’t stop at the icon: the Met Office notes that it won’t represent conditions everywhere, and that a hazard affecting only a small part of the area often gets a lower likelihood [18].

Finally, read the forecast alongside what you know about the route. A trail difficulty rating always assumes good weather and dry ground; a well-estimated hiking time tells you when you’ll be on the very ridge the forecast describes; the keeper of a hut knows the state of the trail; and if you travel without a car, the time of the last bus goes hand in hand with the forecast.

The smart move: before the numbers, read the forecast’s time of issue, its area, and its elevation, then check it again the morning you head out if it’s been updated, as the Met Office does before 6 a.m. [18] Forecasts are like bread: best when they’re fresh.

Guillaume Hoarau

Camping, backpacking, bushcraft and hiking

Guillaume Hoarau writes for Outfarer about camping, backpacking, bushcraft, and hiking. A survival-skills buff and a collector of vintage field manuals, he loves clear explanations, lists that actually help and other people’s stories, which he tells well.

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