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Before a Lightning Storm

  • If you can hear thunder, you are within striking distance. Seek safe shelter immediately!
  • At the first clap of thunder, go to a large building or fully enclosed vehicle and wait 30 minutes after the last clap of thunder before you go back outside.
  • Learn to recognize the signs of a developing storm.
    • Thunder and lightning storms are most likely on spring or summer days (May through August), but they can occur year round.
    • Often the first signs are towering clouds, dark skies and distant rumbles of thunder or flashes of lightning.
    • With heat from the sun, pockets of warming air start to rise and vertical, cauliflower-shaped, cumulus clouds form.
  • Know where you’ll find shelter (a building or vehicle).

Be alert

  • Monitor local weather conditions with an AM/FM or dedicated weather radio.
  • Watch for developing thunderstorms.
  • When you first see lightning or hear thunder, be prepared to implement your plan.
  • Since lightning often precedes rain, don't wait for rain or lightning before taking cover. Lightning can strike as far as 10 miles from the area where it is raining. That's about the distance you can hear thunder. When you see lightning, count the time until you hear thunder. If that time is 30 seconds or less, the thunderstorm is within six miles of you, and it’s dangerous!

Minimize the risk of being struck outdoors

  • Most lightning deaths and injuries occur in the summer, when people are apt to be outdoors.
  • Leaders of outdoors events should have a written plan that all staff are aware of and enforce.
  • Stop outdoor activities at the first sound of thunder to ensure everyone has time to get to a large building or enclosed vehicle.

Minimize risks indoors

  • Lightning can enter a building through a direct strike, through wires or pipes that extend outside the structure or through electrical, phone, plumbing and radio/television antennas. So, if you will be indoors, prepare to avoid contact with corded phones, electrical equipment and plumbing.
  • Since typical surge protectors will not protect equipment from a direct strike, insofar as possible prepare to unplug appliances and electronic equipment, including antenna connections.
  • Buy and use surge suppressors for key equipment.
  • Use ground fault protectors on circuits near water or outdoors.

For more information on lightning, see: