It’s easy to know when a severe threat, such as a tornado, is nearby. An emergency siren alerts your community to seek appropriate shelter immediately. Thunderstorms aren’t announced with much fanfare unless you live in a tornado-prone area, but the risks associated with lightning strikes remain real and hazardous, even when the storm is miles out from your location.It’s a good idea to be aware of how far a storm is from you, so you can determine the likelihood of lightning before venturing outside.

An Old Wives’ Tale With a Grain of Truth

As a child you likely heard the myth that if you count the seconds that pass between a lightning flash and the sound of thunder, that you could assume the storm was an equal number of miles away as those seconds you just counted. This isn’t true, but the reality isn’t far behind. Since light travels faster than sound, you see lightning before you hear thunder. The way to calculate the distance based on this difference in timing is fairly straightforward.

  1. Begin counting seconds when you first see the flash of lightning.
  2. If thunder booms before you get to 5, the storm is within a mile.
  3. For every 5 seconds you count, the storm is a mile out. For example, 10 seconds would mean the storm is 2 miles away, and 15 seconds would mean about 3 miles.

Of course, a live lightning tracker can save you the trouble of counting under your breath. Trackers often show on a map the exact locations of strikes nearby and let you know when lightning is close enough to be a danger.

It’s Not Over Until It’s Over

Just because a storm has passed, doesn’t mean the potential for lightning is gone with it. Lightning can strike as far as 20 to 30 miles away from the parent thunderstorm. Stay safe by remaining indoors until well after the last of the thunder has dissipated. Waiting about half an hour should help you avoid rogue lightning as the storm moves on. Keep up with weather reports in your area to be certain your location is secure.