• Rainbow over Half Dome

    Yosemite

    National Park California

Lightning Safety

How To Avoid Getting Struck By Lightning

Before a Thunderstorm

  • Check the weather forecast.
    Yosemite Valley
    Half Dome
    Glacier Point
    Tuolumne Meadows
    Hetch Hetchy

  • Watch for afternoon build-up of cumulus clouds. At the first sign of an impending storm, such as towering thunderheads, darkening skies, increased wind, or thunder and lightning, seek shelter or get to lower elevations.
    Mountain ridges and peaks contribute to updrafts that fuel thunderstorms. Thunderstorms are most common in the afternoon.

  • Even if a thunderstorm is approaching from a long distance, descend as far and fast as you can before taking shelter.
    Count the seconds between the flash of the lightning and the sound of the thunder; divide the number of seconds by five to get a very rough estimate of the distance (in miles) that the lightning storm is away from you.

    The 30/30 Rule is the best general rule to follow to avoid lightning strikes. If, after seeing lightning, you can’t count to 30 before hearing the thunder, get down off of ridges and mountain tops to lower elevation areas sheltered from lightning strikes. Stay off ridges and mountain tops for 30 minutes after hearing the last clap of thunder.


During a Thunderstorm

Avoiding a thunderstorm before one arrives it the best way to stay safe. If you're unable to avoid a thunderstorm, here are some additional tips.

  • Avoid tall, isolated, or solitary trees, water, metal, and power lines.
    Lightning often strikes the tallest object in the area.

  • Find an open, low space on solid ground. If in the forest with no clearing, position yourself under the shortest trees you can find.
    Seek a place sheltered from direct strikes (avoid high points and tall objects) and ground currents (avoid tree roots).

  • Remove metal objects and electrical devices from your body.

  • Space yourself at least 15 feet from your hiking companions.

  • As a last resort, make yourself a small target by crouching on your toes, hands covering your ears, head between your knees. Crouch down on a sleeping pad, pack, or other non-metal material to insulate yourself from ground currents.
    Touch the ground as little as possible; the ground conducts electricity. Do not lie flat.

  • Stay alert and remain in a safe position until 30 minutes after last thunder.

Did You Know?