Guide · Weather and nature

Thunderstorms and lightning

Lightning is dangerous, but the risk drops sharply when you know the warning signs and act early. Most lightning injuries happen to people who could have reached safer ground in time.

Know when a storm is close

• Count the seconds between a flash and its thunder. Every 3 seconds is about 1 km.
• If the gap is 30 seconds or less, the storm is close enough to strike you. Seek shelter now.
• If you can hear thunder at all, you can be struck. Lightning can hit 10 km or more ahead of a storm.
• Wait at least 30 minutes after the last thunder before going back out.

The safest places

• A solid building with wiring and plumbing.
• A car, van or bus with a hard metal roof, with windows closed. Don't touch metal parts.

Tents, open shelters, huts without wiring and cave entrances do not protect you.

If you're caught outside

1. Get off peaks, ridges and exposed high ground. Head downhill if you can.
2. Avoid isolated trees, poles, masts, fences and metal objects.
3. Get out of and away from water — lakes, rivers, the sea and wet ground near them.
4. In woodland, shelter among lower trees in a dense area, not beside the tallest one.
5. Avoid the mouths of caves and overhangs, where current can jump across the gap.

If there's nowhere to go

Make yourself small and keep your contact with the ground small:

• Crouch on the balls of your feet, feet together, head down and hands over your ears.
• Sit on a dry, insulating mat or rucksack without metal parts if you have one.
• Don't lie flat on the ground.

This doesn't make you safe, but it may reduce the risk while you wait.

In a group

Spread out at least 15 metres apart. If lightning strikes, it is less likely that everyone will be hurt, and others can help.

Warning signs of a close strike

Hair standing on end, a tingling feeling, buzzing from metal objects or a blue glow around rocks can mean a strike is about to happen. Move away from the spot at once if you can, or crouch immediately.

Helping someone who has been struck

• People struck by lightning do not carry an electrical charge. It is safe to touch them.
• Call your local emergency number (112 in Europe and many other countries, 911 in North America).
• If they are not breathing normally, start CPR at once and keep going until help arrives.
• Check for burns and other injuries, and keep them warm.

Other storm dangers

Thunderstorms also bring sudden strong winds, hail and heavy rain that can cause flash floods. Stay away from streams and narrow valleys during and after a storm.

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