Lightning fact sheet
Rebecca S. Blocker, Housing and Environmental Design Specialist, St. Francois County, University of Missouri Extension
With thunderstorm season upon us, understanding lightning can help you make safer decisions when storms threaten.
- If you hear thunder, lightning is near. Just because it’s not raining, doesn’t mean you aren’t in danger.
- Most people are struck by lightning before or after the thunderstorm.
- Lightning kills more people in the U.S. than tornadoes and hurricanes combined.
- Outdoor sports have the fastest rising lightning casualty rate.
- The National Weather Service and the National Oceanic and Atmospheric Administration (NOAA) reports top activities for lightning deaths are in open fields, under trees, in open vehicles, doing water-related activities, golfing, using the telephone and using radio equipment.
To reduce your risk of injury or death, follow the 30/30 Rule
and use the Flash to Bang Calculator.
- 30/30 Rule: If you hear thunder within 30 seconds after seeing the flash, move indoors quickly and stay inside until 30 minutes after the last thunder.
- The Flash to Bang Lightning Distance Calculator: If you see lightning, count the seconds until you hear thunder, then divide by 5. This is the distance in miles the lightning is away. Any distance less than 10 miles puts you in danger. Seek shelter immediately.
There is no place outside that is safe in or near a thunderstorm.
The safest shelter is inside a building with wiring and plumbing.
- You can be injured inside your house. Stay away from windows, doors, plumbing, appliances, electronics or anything that conducts electricity.
- Use cell phones or cordless phones. Most people injured by lightning are talking on a corded phone.
- Do not take a shower, bath or hot tub if you hear thunder or for 30 minutes after.
- Unplug computers and electronics. Don’t rely on surge protectors.
- Lightning rods will not prevent getting hit, but should direct current to the ground along a preferred path.
- Picnic shelters/pavilions, baseball dugouts, carports, porches and buildings with exposed openings are not safe (even if grounded).
An enclosed vehicle with metal roof and sides (automobile, van
or school bus) is the next best alternative if no safe building
- Roll up the windows and avoid contact with the radio, CB and ignition.
- Convertibles (even with the top up), golf carts, mowers and vehicles with open cabs are not safe.
If you are caught outside and you feel your hair stand on end,
squat down, tuck your head as low as you can and cover your ears.
- Do not lie flat on the ground. When lightning strikes the earth it can be fatal up to 100 feet away. Minimize height and contact with the ground.
- Stay away from tall trees, poles, wire fences, clotheslines
and metal pipes. Lightning does not always strike the tallest
object, only the tallest object in a particular area.
For more information, visit the National Weather Service and NOAA lightning safety website at lightningsafety.noaa.gov.
Last update: Monday, June 22, 2015