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Thunderclouds over a mountain meadow, hikers descending to the valley

A thunderstorm is coming and I am outdoors

Clouds are towering up, the wind is picking up, thunder rumbles in the distance – there is no truly safe place outdoors, but there is a lot you can do right now.

First

  1. If you can hear thunder, you are within reach of lightning: stop the activity and seek shelter.
  2. Safe places are substantial buildings and enclosed vehicles with a metal roof – not tents, open shelters or isolated trees.
  3. Leave summits, ridges, open areas and water at once; as a group, spread out.
  4. Only go back outside once the storm has clearly passed.

Call emergency services if

  • Someone has been struck by lightning – they carry no electrical charge and can be touched immediately
  • Unconsciousness or no normal breathing
  • Injury from a fall or falling branches
  • Signs of hypothermia after wet and cold

Emergency numbers for Austria · Change region

What is happening

In summer, thunderstorms often build within a few hours, in the mountains typically in the afternoon. Warning signs are clouds towering rapidly upwards with dark bases, freshening gusty wind and the first distant rumbles. If you only react at the first close flash, you have usually already lost valuable time.

Lightning can strike well ahead of the storm front itself, often before the rain arrives. That is why: if you can hear thunder, you are within reach. The danger is not only a direct strike: the current spreads through the ground, water and wet rock and can also hit people nearby, and it can jump from a struck tree or pole to people standing next to it.

Then come the secondary hazards: heavy rain makes gullies and streams swell quickly, hail and gusts break off branches, wet rock becomes slippery, and after the storm soaked people cool down quickly – especially at altitude.

Typical misjudgements are “it will pass us by”, sheltering under an isolated tree, waiting it out in a tent or an open-sided shelter, and moving on too soon. What really matters: take the forecast seriously before the trip, turn back early, leave exposed places in good time and wait in substantial buildings or enclosed vehicles with a metal roof.

Step by step

  1. Phase 1

    At the first signs

    • Check the weather and warning app; watch how clouds and wind develop.
    • Adjust your plan: turn back or head for the nearest hut, substantial building or car.
    • Leave summits, ridges, via ferratas with steel cables and open ground early.
    • Get out of the water – whether swimming or in a boat.

  2. Phase 2

    When you hear thunder

    • Go at once into a substantial building or an enclosed vehicle with a metal roof and close the windows.
    • If that is out of reach: leave exposed spots and move to lower areas – but not into gullies or stream beds.
    • Keep away from isolated trees, poles, metal fences, steel cables and power lines.
    • Spread out as a group, but stay within calling and sight distance so you can help each other.
    • Put on rain gear and a warm layer before you are soaked.

  3. Phase 3

    During the storm

    • Inside a building, stay away from windows and avoid contact with plumbing and corded devices.
    • In a vehicle, stay seated with the windows closed.
    • Outdoors: there is no position that makes you safe. Do not lie flat on the ground; if possible, keep moving away from exposed spots.
    • Look after the group: is everyone there? Is anyone getting cold? Is water rising nearby?

  4. Phase 4

    Afterwards

    • Only go back outside about 30 minutes after the last thunder.
    • Change wet clothing, eat and drink, watch for signs of hypothermia.
    • Check the route for new hazards: swollen streams, rockfall, broken branches, slippery rock.
    • If someone has been struck by lightning: call the emergency number (112 in the EU) – they carry no electrical charge and can be touched immediately. Check breathing and follow the dispatcher's instructions.

What to watch out for

  • Lightning comes before the rain

    Lightning often strikes before the rain arrives, and after the storm has moved on. Blue sky overhead does not mean you are out of reach.

  • Current in the ground

    After a strike, current spreads through the ground, wet rock and water. That is why spacing within a group reduces the risk that several people are affected.

  • Steel cables and metal fences

    Fixed cables on via ferratas and long fences can carry current over long distances. Get off a via ferrata early.

  • Flash floods in gullies

    Heavy rain can make gullies, gorges and streams swell very fast, also from rain further up. Do not shelter there.

  • False sense of safety

    Tents, open-sided shelters, cave entrances and rock overhangs do not protect from lightning. They only keep the rain off.

  • Getting cold after the storm

    Thunderstorms often bring a marked drop in temperature. Anyone soaked and standing in the wind can get dangerously cold, even in summer.

Common mistakes

  • Waiting too long because the storm still seems far away.
  • Sheltering under an isolated tree or at the forest edge.
  • Waiting it out in a tent or an open-sided shelter.
  • Pushing on to the summit despite building storms.
  • Huddling close together as a group.
  • Moving on too soon, as soon as the rain eases.

Prepare in advance

  • Check the forecast and thunderstorm risk before every trip and install an official warning app.
  • Start early and set a turnaround time before the typical thunderstorm hours.
  • Know where along the route substantial buildings, huts or your car can be reached.
  • Always carry rain protection and a warm layer.
  • Take a first aid course.

Special consideration

Children
Thunderstorms frighten many children. Explain calmly what you are doing and why, and keep them right beside you – even if the rest of the group spreads out.
Dogs
Many dogs panic at thunder and run away. Keep your dog on a short lead.

Sources

  • Lightning Safety · NOAA National Weather Service (USA)
  • Thunderstorms & Lightning · Ready.gov – U.S. Federal Emergency Management Agency (FEMA)
  • Mountaineering: The Freedom of the Hills, 9th edition · The Mountaineers Books, 2017

Your situation

Terrain
Shelter within reach

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All rules of this situation (7)

  1. [not active] If Shelter within reach = None of these

    There is no safe place outdoors. Leave exposed spots, move to lower areas – but not gullies with running water – and spread out as a group. This reduces the risk but does not remove it.

  2. [not active] If Shelter within reach = Substantial building

    Go into the building and stay inside until the storm has passed. Keep away from windows.

  3. [not active] If Shelter within reach = Car with a metal roof

    Get into the vehicle and close the windows. Convertibles and vehicles with plastic bodies do not give this protection.

  4. [not active] If Terrain = Mountains

    Leave summits and ridges at once. Next time, plan the turnaround time so that exposed places are left before the typical thunderstorm time.

  5. [not active] If Terrain = Forest

    There is no safe spot in the forest either. Avoid isolated or prominent trees and watch for falling branches.

  6. [not active] If Terrain = Open ground, field

    On open ground, move quickly to a building or vehicle. Keep away from metal fences, poles and power lines.

  7. [not active] If Terrain = At or on the water

    Leave the water at once – whether swimming or in a boat – and seek shelter on land.