What is the 30/30 rule for lightning?

If thunder follows lightning by 30 seconds or less, seek shelter immediately. Wait 30 minutes after the final thunder before going back outside.

How far away can lightning strike from a storm?

Strikes routinely occur 10 to 15 miles from the parent storm, sometimes from apparently clear sky overhead.

Lightning Safety: The 30/30 Rule Explained

Lightning kills more Americans in a typical year than tornadoes. Nearly all of those deaths happen to people who were outdoors and thought they had more time.

Inside a storm cloud, colliding ice particles separate electrical charge, lighter positive particles carried up, heavier negative ones sinking. The difference builds until the air can't insulate it any longer, and a channel of superheated plasma equalizes it in microseconds. That channel reaches roughly 50,000°F, about five times the surface of the sun, and the explosive expansion of air around it is thunder.

Counting to the strike

Light arrives instantly; sound travels about a mile every five seconds. Count the seconds between the flash and the thunder, divide by five, and you have the distance in miles. Fifteen seconds means three miles away.

THE 30/30 RULE

If the gap between flash and thunder is 30 seconds or less, the storm is within about six miles, go inside now. Stay inside for 30 minutes after the last thunder you hear. Most lightning deaths happen before the rain starts or after it stops.

Bolts from the blue

Lightning regularly strikes 10 to 15 miles from the parent storm, out of sky that looks clear overhead. If you can hear thunder at all, you are within range. There is no such thing as being safely near a thunderstorm outdoors.

What actually counts as shelter

Safe: a substantial building with wiring and plumbing, or a hard-topped vehicle with the windows up (it's the metal shell conducting around you, not the tires).
Not safe: picnic shelters, dugouts, porches, tents, golf carts, convertibles, or anything open-sided.
Indoors, still avoid: corded phones, plumbing, and leaning against exterior concrete walls with embedded metal.

If you're caught with nowhere to go

Get off high ground, away from isolated trees, water, and metal objects. Spread your group out. Crouching low with feet together used to be standard advice and is now considered a last resort rather than a safe position. It reduces risk slightly but is not protection. The only real answer is getting to a building or vehicle before you need it.

Struck people are safe to touch

A lightning victim carries no residual charge. Cardiac arrest is the primary cause of death, and immediate CPR saves lives. Call 911 and begin compressions, hesitating helps no one.