Estimate how far away a thunderstorm is by counting the time between a lightning flash and the sound of thunder. Enter the delay to calculate storm distance in miles, kilometers, feet, and meters.
Flash-to-thunder delay:
Enter the time between seeing lightning and hearing thunder.
Simple method:
The simple rule estimates about 5 seconds per mile, or about 3 seconds per kilometer.
Temperature adjusted method:
This option estimates distance using the speed of sound adjusted by air temperature.
Storm distance:
The calculator converts the result into miles, kilometers, feet, and meters.
A thunderstorm distance calculator is useful for storm tracking, outdoor work, camping, hiking, boating, sports, event planning, and deciding when a storm is close enough to take shelter.
This is an estimate only. If you hear thunder, lightning is close enough to be dangerous, so follow official weather alerts and local safety rules.
Your result estimates how far the thunderstorm is from your location. Shorter time delays mean the storm is closer. Longer time delays mean the storm is farther away.
Count the seconds between lightning and thunder, then divide by about 5 to estimate the distance in miles.
Using the simple rule, a 10-second delay means the storm is about 2 miles away.
Using the simple rule, a 30-second delay means the storm is about 6 miles away.
Light travels much faster than sound, so the lightning flash reaches you before the thunder sound does.