Lightning safety

The rules that matter

• Go indoors at the first thunder. Lightning can reach about 10 miles from a storm — roughly as far as you can hear thunder.
• Safe shelter is a substantial building with electricity or plumbing, or an enclosed, metal-topped vehicle with the windows up. Picnic shelters, tents and open porches are not.
• Wait 30 minutes after the last thunder before going back outside.

How far away is the storm? Flash to bang

Count the seconds between the lightning flash and the thunder, then divide by five to get the distance in miles: 5 seconds ≈ 1 mile, 15 seconds ≈ 3 miles, no gap means it is right on top of you. Thunder can usually be heard only about 10 miles away, so if you hear it at all, you are in range.

Indoors

• Avoid corded phones, computers and other electrical equipment.
• Avoid plumbing — sinks, baths and faucets.
• Stay away from windows and doors, and off porches.
• Don't lie on concrete floors or lean on concrete walls.

Caught outside

There is no safe place outside in a thunderstorm; these steps only lower the risk while you head for shelter:

• Get off elevated areas such as hills and ridges.
• Never lie flat on the ground.
• Never shelter under an isolated tree or a rocky overhang.
• Get out of and away from water immediately.
• Stay away from things that conduct electricity — wire fences, power lines, metal poles.

Lightning facts

Lightning is a giant spark of electricity in the atmosphere or between the atmosphere and the ground. It can heat the air to about 50,000 °F, and the US sees about 25 million lightning flashes a year, according to the National Weather Service. Your odds of being struck are small — see the odds of being struck by lightning — but most victims were outdoors when a storm was nearby.

Frequently asked questions

Sources

• NWS — Lightning safety tips
• NWS — Lightning safety
• NWS — Thunder
• NWS — Lightning science overview