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Lightning Safety: What to Do Before, During and After a Storm

By Noureddine, developer of Lightning Map · Published · Updated

Lightning kills about 20 people a year in the United States, and hundreds more are injured, some with lifelong nerve damage (NWS). In the UK, between 1988 and 2012, an average of two people a year were killed and around 30 injured (TORRO). Many victims say they were caught outside and couldn't get to a safe place in time (NWS).

The rules that prevent this are short and easy to remember. This guide explains them, with links to the official sources so you can check everything yourself.

The short version: when thunder roars, go indoors. Get into a solid building or a hard-topped car, and wait 30 minutes after the last thunder before going back out.

How lightning hurts people

Lightning doesn't have to hit you directly. The US National Weather Service describes five ways people are injured (NWS):

  • Direct strike: you become part of the lightning's path. This is less common, but often deadly.
  • Side flash: lightning hits something tall nearby, such as a tree, and part of the current jumps to you.
  • Ground current: the current spreads out through the ground from the strike point. The NWS says this causes the most lightning deaths and injuries, because it affects a large area.
  • Conduction: the current travels along metal fences, wires or plumbing to someone touching them, indoors or out.
  • Streamers: small upward discharges that can injure people near a strike.

That's why "it didn't hit me" isn't the same as "I was safe". Being near a strike is enough.

Before the storm

Check the forecast

Before a hike, a round of golf, a match or a day on the water, check your national weather service's forecast for thunderstorms, not just rain. The Met Office advises changing your plans if storms are forecast where you're going (Met Office).

Know where you'll shelter

Decide in advance where you'll go if a storm comes: a building, or your car. On a sports field, a campsite or a trail, the time to make that plan is before you set off, not when you hear the first rumble.

If you can hear thunder, you're in range

"If you hear thunder, lightning is close enough to strike you" (NWS). Lightning can strike 10 to 15 miles (16 to 24 km) from the storm, sometimes under a blue sky (NWS myths).

You may have heard of counting the seconds between flash and thunder. Sound travels about 1 mile in 5 seconds (1 km in 3 seconds), so it gives a rough distance. But don't use it to decide whether you can stay outside: if you can hear thunder at all, go inside.

During the storm: where is safe?

"There is no safe place outside when thunderstorms are in the area" (NWS). Only two kinds of shelter protect you.

Safe places

  • A substantial building with electricity or plumbing: a house, school, shop or office (NWS).
  • A hard-topped metal vehicle with the windows closed. The metal body carries the current around you to the ground. The rubber tyres do nothing (NWS myths; Met Office).

Not safe, even if they keep you dry

  • Trees: never shelter under an isolated tree (NWS).
  • Sheds and open structures: picnic shelters, covered porches, gazebos and bus stops (NWS; Met Office).
  • Tents: "a tent offers NO protection from lightning" (NWS).
  • Caves, cliffs and rock overhangs (NWS).
  • Open vehicles: convertibles, motorbikes, bicycles, golf carts and cars with fibreglass bodies (NWS myths).

Once you're indoors

The NWS advises (NWS):

  • stay off corded (landline) phones, computers and other equipment plugged into the mains. Cordless and mobile phones are safe to use (NWS);
  • avoid plumbing: sinks, baths, showers and taps;
  • stay away from windows and doors, and off porches;
  • don't lie on concrete floors or lean against concrete walls.

If you're caught outside with no shelter

This is a last resort, not a safe alternative. Keep moving towards a building or car if you can. Meanwhile:

  • avoid open areas, and don't be the tallest object around (NWS);
  • get off hills, ridges and peaks straight away;
  • get out of and away from water: lakes, ponds, rivers and the sea;
  • stay away from tall isolated objects, and from metal fences, power lines and other things that conduct electricity;
  • put down metal objects such as golf clubs, fishing rods and umbrellas (Met Office);
  • if you're in a group, spread out, so one strike can't injure everyone and someone can help if a person is hit (NWS);
  • never lie flat on the ground (NWS).

About the "lightning crouch": official advice differs. The UK Met Office still says to squat low with your head tucked down and as little contact with the ground as possible, and to do so immediately if your hair stands on end (Met Office). The US National Weather Service stopped recommending it in 2008, because it doesn't give a significant level of protection and can make people think they're safe outside (NWS). Both agree on what matters most: don't lie down, and get to real shelter.

After the storm: the 30-minute rule

"Stay in safe shelter at least 30 minutes after you hear the last sound of thunder" (NWS).

Not when the rain stops, and not when the sky brightens. "Many lightning deaths occur ahead of storms before any rain arrives or after storms have seemingly passed and the rain has ended" (NWS). Every new rumble of thunder restarts the 30 minutes.

For more on where the rule comes from and how to apply it in sport, swimming and work, see the 30-minute lightning rule.

The same rule is used for outdoor workers (OSHA and NOAA) and in sport, where the National Athletic Trainers' Association's position statement uses it to decide when play can restart (NATA).

Situations with extra risk

Sports matches and training

Fields are open, and there's pressure to "just finish the game". The NATA recommends that every venue has a lightning plan, with one named person who has the authority to stop play, a reliable way to monitor the weather, and safe shelter identified in advance (NATA). Partly open shelters, such as dugouts, picnic shelters and bus stops, don't count as safe shelter (NATA).

Golf

A golf course combines open ground, isolated trees, water and metal clubs. The Met Office lists golf among the activities to avoid in a thunderstorm (Met Office). At the first thunder, put the clubs down and head for the clubhouse or your car. A golf cart is not shelter (NWS myths).

Hiking and camping

Height and exposure increase the risk, and in the mountains shelter can be hours away. Check the forecast before you go, turn back early if storms start building, and get off peaks and ridges as soon as you hear thunder. Don't shelter in caves or under rock overhangs (NWS). A tent offers no protection; if you're in one, stay away from metal poles (Met Office).

On or near water

Boating, swimming, fishing and beach days put you in the open, often far from shelter. Get off the water and away from the shore before the storm arrives. The Met Office advises against rod fishing and boating on lakes during thunderstorms (Met Office).

Working outdoors

In the US, OSHA and NOAA say employers should have a written emergency action plan with a lightning procedure: how workers are warned, where the safe shelters are, how long it takes to reach them, and when work stops and restarts (OSHA and NOAA).

If someone is struck

Call the emergency services straight away (911 in the US, 999 or 112 in the UK and Europe). "The human body does not store electricity. It is perfectly safe to touch a lightning victim to give them first aid" (NWS myths).

People killed by lightning die of cardiac arrest, so the NWS advises (NWS):

  • begin CPR if you're trained;
  • use an automated external defibrillator (AED) if one is available;
  • if possible, move the victim to a safer place: lightning can strike the same place twice.

Using a live lightning map

A live map helps you see storms before you hear them: where lightning is striking, how widespread it is, and which way it's moving. That's useful when deciding whether to start a hike, a match or a trip.

Know the limits of the map you use. On Lightning Map, strikes in the Americas usually appear within about a minute, but in Europe and Africa the satellite data arrives in 10-minute batches, so it is 10 to 12 minutes old (how our data works). Satellite locations are also approximate: the detectors see the ground in squares roughly 5 to 15 km wide.

So use a map to plan ahead and to watch a storm coming. When it comes to the 30-minute rule, trust your ears: if you hear thunder, go inside, and wait 30 minutes after the last rumble.

Lightning safety FAQ

What is the 30-minute rule?

Stay in a safe building or hard-topped car for at least 30 minutes after the last thunder you hear. Each new rumble restarts the 30 minutes. It is the rule recommended by the US National Weather Service.

Is it safe to go outside when the rain stops?

Not necessarily. Lightning can strike miles from the rain, including from the back of a storm that is moving away. Wait 30 minutes after the last thunder, even if it has stopped raining.

Where is the safest place during a thunderstorm?

Inside a substantial building with electricity or plumbing, away from windows, plumbing and corded electrical equipment. The next best place is a hard-topped metal car with the windows closed.

Am I safe in a car during lightning?

Yes, in a hard-topped metal car with the windows closed. The metal body carries the current around you. Tyres don't protect you, and convertibles, motorbikes, bicycles and golf carts are not safe.

How far can lightning strike from a storm?

The US National Weather Service says lightning can strike 10 to 15 miles (16 to 24 km) from a storm, sometimes from a clear sky. If you can hear thunder, you are close enough to be struck.

Should I lie down or crouch if I'm caught outside?

Never lie flat. The UK Met Office advises squatting low with as little ground contact as possible as a last resort. The US National Weather Service no longer recommends the crouch, because it gives little protection. Both say the priority is getting to a building or car.

Is it safe to shower or use the phone during a thunderstorm?

Avoid showers, baths, taps and corded landline phones, because lightning can travel through plumbing and phone lines. Cordless and mobile phones are safe to use, according to the US National Weather Service.

Can you touch someone who has been struck by lightning?

Yes. People struck by lightning do not carry an electrical charge. Call the emergency services, start CPR if you're trained, and use a defibrillator (AED) if one is available.

Sources

This guide is for general information. Always follow warnings from your national weather service and local authorities.