How to read mountain weather: These planning tips & warning signs you should know

This applies to beginners and professionals alike: every tour depends on the weather conditions in the mountains. We'll show you what's important when planning mountain tours to avoid dangerous situations caused by sudden weather changes or thunderstorms, and how to react correctly in an emergency.

Why the weather in the Alps is so difficult to predict

The weather in high mountains differs significantly from that in lower-lying regions for several reasons. In the Alps, moist air masses are forced to rise, causing clouds to form and large amounts of precipitation to fall. Overall, the weather in the mountains is complex. Interaction of countless factorsAir pressure, humidity, temperature, wind, sun – to name just a few.

In very simplified terms, Alpine weather can be explained as follows: Within the large-scale European weather pattern, the Azores High, the Icelandic Low, and the Gulf Stream influence the weather in Central Europe. At the same time, the Alps form their own complex weather system with strong regional differences and pronounced local effectsThis is because the rugged terrain of the mountains constantly forces air masses to rise and fall, diverting their flow in different directions. This creates highly varied weather conditions within a very small area, which... Precise forecasting of Alpine weather remains challenging to this day. .

Mountain weather basics: High and low pressure explained

Low pressure system: A low-pressure area is a part of the Earth's atmosphere with relatively low atmospheric pressure. In a low-pressure area, the air rises. This can lead to the formation of clouds and precipitation, which, depending on temperature and altitude, can result in changeable weather with rain or snow over the Alps. With frequent Italian or Mediterranean low pressure system Moist, warm air from the south glides over the colder air from the east, often causing heavy snowfall in the southern and eastern Alps, as well as flooding in the summer.

High pressure situation: A high-pressure area is a large air mass near the ground that has a higher air pressure than the layers above it. A large high-pressure system over Central Europe and the Alps is particularly welcome to hikers and mountaineers. This is because cold air and fog accumulate in the valleys, while the sun usually shines on the mountains. Another advantage: unlike low-pressure systems, high-pressure systems often remain in one place for several days and move on more slowly.

Foehn conditions: Foehn wind is a warm, dry wind that descends from the Alpine peaks into the valleys (fall wind). It can blow steadily or be gusty and usually causes temperatures to rise rapidly. On the mountains, the foehn is most often experienced along the ridge, but also in the valleys or the Alpine foothills. Typical of foehn weather are the characteristic lenticular clouds, which can look like stacked pancakes. There are many other winds in the Alps, such as the cold fall winds Bora and Mistral.

Typical weather patterns in the Alps

North-facing slope: When high pressure prevails over the Atlantic and low pressure over northeastern Europe, cold, moist air from the north is forced upwards towards the Alps. This often leads to heavy snowfall in the northern and central Alps, while it remains sunny and windy on the southern side of the Alps.

Westerly location: Moist Atlantic air from the west flows into Central Europe, producing several low-pressure systems in succession, some of which can last for over a week. In summer, this leads to strong thunderstorms along cold fronts, while in winter, heavy snowfall occurs in the Western Alps and the Arlberg region. Eastern Europe generally receives less precipitation due to the westerly flow.

Thunderstorm situation: Thunderstorms in the Alps are particularly common in summer, when strong sunlight, high humidity, and volatile air currents combine. A distinction is made between locally developing thunderstorms. heat thunderstorm and front thunderstormThese storms originate along cold fronts. From May to September, heat thunderstorms pose the main danger to mountaineers, while frontal thunderstorms can occur at any time of year. Approximately 90 percent of all thunderstorms in Germany occur between June and August.

Severe weather events are measured differently based on the amount of snowfall and precipitation, depending on altitude and time period. This becomes especially life-threatening Lightning strikesA strong lightning strike can briefly carry a current of up to 400.000 amperes – this is roughly equivalent to the power consumption of tens of thousands of household appliances simultaneously.

Tour planning: Important weather services and apps

Of course, you don't need to be a meteorologist to be a mountaineer – because today, in addition to conventional weather services, there are also special forecasting tools for localized weather in the mountains. Ideally, for the safest possible tour planning, you combine data from several reports, supplemented by your own know-how and on-site observations.

As a general rule, modern forecasts are quite accurate starting three to four days in advance. The closer to the start of your trip you check the forecast, the more reliable it is. We therefore recommend checking the various weather reports daily from three days before the start of your tour.

However, even the most advanced apps shouldn't be relied upon completely: because correct interpretation of weather data often requires... many years of mountaineering experienceThis article cannot replace that. Even the best preparation cannot guarantee that the weather on the mountain will not go according to plan.

Online services

• National weather services
  Besides well-known weather websites, the websites of the national weather services are relevant for the Alps: DWD (Germany), ZAMG (Austria), Meteo Switzerland, Meteo France and South Tyrol.
• Alpine weather radar from Wetteronline 
  A clear but less detailed report on the weather situation in the Alpine region, with a forecast for the next two to four days. Suitable as a first overview, but not recommended as the sole source for tour planning.
• DAV-Wnewsletter report & ÖAV weather report
  Current weather forecast for the Eastern and Western Alps for the next three to five days. The German Alpine Club (DAV) also includes a "thunderstorm traffic light" with different warning levels in its report. Ideal for planning day trips and weekend tours. The Alpine Club reports are published daily from around 16 p.m.
• Weather center
  Here, all weather data available online worldwide is collected and processed – including current expert assessments. Features include detailed weather maps for various regions, extreme value analyses, and an archive of maps based on different reanalyses. Anyone willing to delve a little deeper into the subject will find current, comprehensive data and forecasts here.
• Meteomedia
  Extremely detailed, regional forecasts from hundreds of weather stations in Germany, Austria, and Switzerland (also: Liechtenstein and Belgium). Data includes temperature and wind forecasts, as well as information on humidity, hours of sunshine, and precipitation. Forecasts are displayed for up to 14 days and provide the most important weather parameters for the respective region in the coming days. Especially helpful for anyone hiking in the mountains in the summer or ski touring in the winter.

Apps

• Bergfex (iOS & Android)
  A popular, user-friendly mountain weather app with free and detailed daily forecasts for up to nine days, including precipitation predictions, temperature, wind, and sunshine duration. The Pro version, available for €3,99 per year, offers additional data from over 200 weather stations and a daily webcam archive.
• Meteoblue (iOS & Android)
  Considered one of the best free apps for the mountains, Meteoblue offers pinpoint weather forecasts for almost every mountain peak, clear meteograms (temperature, wind, cloud cover), and displays the accuracy of the forecast based on various weather models. Weather forecasts are updated twice daily.
• Windy (iOS & Android)
  Ideal for detailed wind and weather models (such as ICON or ECMWF). The free version of Windy offers many features and hourly forecasts, particularly useful for assessing wind gusts at the summit. The paid version adds even more frequent updates, more detailed forecast maps, and is ad-free.

Warning signs: When should I turn back?

As a general rule: Anyone who decides to go ahead with the tour despite uncertain weather conditions should Start as early as possibleBecause summer thunderstorms often occur in the afternoon, the German Alpine Club (DAV) recommends reaching the summit by midday. Furthermore, one should familiarize oneself with the weather conditions beforehand. Protection options such as huts or alpine pastures, or provide information or a Emergency descent Plan ahead. If in doubt, don't wait until the weather has already deteriorated to turn back.

When it's smarter to turn around in time

If you started your journey in mixed conditions, it's advisable to regularly check the weather forecast while on the road. In addition to the apps and services mentioned above, you should also pay attention to important warning signs in your surroundings:

Early cumulus clouds: If large cumulonimbus clouds form in the sky in the morning or forenoon, severe thunderstorms are likely in the afternoon.
Humid air: If it is already oppressively warm and humid in the early morning, the risk of thunderstorms increases significantly.
Sudden pressure drop: A rapid drop in air pressure is a clear warning sign of thunderstorms.
Thunder rumbles in the distance: If you hear a thunderstorm approaching, you should turn around.
Poor visibility: If fog rolls in or visibility drops drastically, there is a risk of disorientation – turn back!
Time exceeded: If it becomes clear that the summit will not be reached by early afternoon, you should turn back.
Gut feeling: Trust your intuition – turning back in time is not a sign of weakness, but can save lives.

When do I need to seek shelter?

How far away a thunderstorm is can be estimated with a simple rule of thumb: Count the seconds between the flash of lightning and the sound of thunder and divide that number by three. If you only count... ten seconds, lie approximately between one's own location and the thunderstorm three kilometersEven at this distance, lightning can strike in the immediate vicinity. At that point, at the very latest, it's time to seek shelter!

The most important signs that it's about to start

Thunderstorms nearby: Only about 10 seconds between lightning and thunder – that corresponds to a distance of only about 3 kilometers.
Dark, towering clouds: Typical are mighty cumulonimbus clouds, often with an anvil-shaped cloud top.
Gusty winds increasing: A sudden increase in strong winds can herald an approaching thunderstorm.
Electric charge: A buzzing or crackling sound in the air, as well as hair suddenly standing on end, can indicate a strong electric field.

In case of emergency: Get to safety and minimize risks

If a thunderstorm is approaching and turning back is no longer possible, you should seek shelter immediately. The safest option is... Shelter with suitable lightning protection systemIf that is not an option, it is necessary to leave exposed areas and reduce personal risk as much as possible.

You should avoid that.

Exposed ridges and elevations, especially summit crosses and rock towers
Via ferratas and secured passages, because there is an increased risk of lightning strikes here
Forest edges and freestanding trees – the saying “Avoid oaks, seek beeches” is not reliable protection!
Niches in or under freestanding boulders
waters every kind
tents, which do not offer reliable lightning protection

Where you can seek protection instead

If no shelter is accessible, Rock caves one possible alternative. You should maintain a distance of at least... 1,5 meters to the rock face comply. Also Hollows in mountain meadows are safer than exposed, flat terrain. If you are in the forest during a thunderstorm, it is safer inside than at the edge of the forest or under a single, isolated tree.

Take a protective position

If the thunderstorm is directly overhead, the German Alpine Club (DAV) and the Austrian Alpine Club (ÖAV) recommend taking a protective position: crouch down with closed and drawn-up legs Place it on a surface that is as insulating as possible, such as a dry backpack or a rope. The aim is to keep the contact area with the ground as small as possible and thus reduce the risk from so-called stray currents. Important: Remain calm and avoid unnecessary movements.

You should keep this in mind

• Metallic equipment Place (ice axes, crampons, trekking pole tips) with sufficient distance between them.
• Distance to tour partners enlarge to reduce the risk of a joint impact
• Heavy rain and rockfall Take into account – the thunderstorm may create additional dangers
• In Stay secure even in terrain prone to falls.
• mobile place in the middle of the backpack

Checklist for your next mountain tour

• Weather check: Check the weather forecast regularly three days before the tour, comparing several regional weather services if possible.
• Tour planning: Start early and, in unstable weather conditions, reach the summit by early afternoon if possible, avoiding long and exposed routes. Keep an eye on the remaining time and the weather development during the tour.
• Contingency plan: Check possible protective measures in advance and allow sufficient time for an unplanned descent.
• Recognize warning signs: During the tour, pay attention to the first signs of an approaching thunderstorm and turn back in time.

This equipment should always be with you.

Rain jacket or hardshell jacket: Protection from wetness and wind, and therefore from cooling down.
Bivouac sack or emergency blanket: Heat retention during longer waiting times or in an emergency situation
First aid kit: For treating minor injuries and as a basis for first aid
Headlamp & spare batteries: Essential in case of an unplanned descent or as part of the alpine emergency signal
Smartphone & Powerbank: For emergency calls, weather information, navigation and GPS – especially important in emergencies
Map & Compass: As a reliable backup in case of empty battery, GPS failure or lack of mobile network reception.
Sufficient water and energy-rich snacks
Warm extra shift: Even in summer, temperatures in the mountains can drop quickly.

That might interest you

• Falls, blockages, thunderstorms: What the Austrian Alpine Club's summer update reveals about mountain accidents in summer
• How to behave correctly during a thunderstorm on the mountain

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Image credits: Adobe Stock/Standard License, Massimo De Candido, File No. 169702027

Sources

• Mountain Friends: An Introduction to Mountain Weather
• DAV: Alpine weather & the Alpine weather kitchen
• DAV: Severe weather in the mountains: What you need to know
• Markus Stadler: Mountain Weather – Weather links and information for mountaineers
• Austrian Alpine Club (ÖAV): Thunderstorms in the mountains: 5 rules of conduct for emergencies

further reading

• German Alpine Club (ed.) (2013): Alpine Curriculum Volume 6: Weather and Orientation. Munich: Bergverlag Rother.
• Keidel, Claus (2004): Mountain Weather: The Handbook for Hikers and Mountaineers. Munich: Bruckmann Verlag.
• Thillet, Jean-Jacques/Schueller, Dominique (2010): Weather in the Mountains. Munich: Bergverlag Rother.
• Plöger, Sven/Schlenker, Rolf (2022): The Alps and how they influence our weather. Munich: Piper Verlag.