How to Calculate Lightning Strike Distance

Lightning is a natural occurrence that can be extremely dangerous. Knowing how to estimate the distance you are from a thunderstorm is an important skill for staying safe during storm season. Pinpointing the exact location of a storm is a job reserved for meteorologists who use complex radar equipment. However, there is a way to estimate your distance from a lightning strike using only your eyes, ears and some fingers to help with counting.

Things You'll Need

  • Stopwatch


    • 1

      Move to a safe vantage point from the thunderstorm for observation.

    • 2

      Start your stopwatch -- or begin counting to yourself -- as soon as you see a flash of lightning. Stop counting when you hear a clap of thunder after the lightning strike.

    • 3

      Divide the number of seconds you counted between lightning flash and thunder by 5. This is the distance between you and the lightning, measured in miles.

Tips & Warnings

  • Don't assume that you are safe just because lightning is several miles away. Even a storm that is many miles away can produce dangerous lightning in your area. A typical lightning bolt is several miles long, and lightning has been known to strike as far as 25 miles from an active thunderstorm.
  • Be mindful that the distance estimate here is only a rough approximation of the actual distance between yourself and a bolt of lightning.
  • The actual speed of sound varies with temperature, so the accuracy of the estimated distance will vary as air temperature near the storm rises and falls.
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  • Photo Credit George Marks/Retrofile/Getty Images

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