Approximately 100,000 thunderstorms occur each year in the United States, with only 10 percent being classified as severe. However, all thunderstorms are dangerous. They produce lightning, heavy rain that can lead to flash flooding, strong winds, hail and tornadoes. Thunderstorms most often occur in the spring and summer months and during the afternoon and evening hours, but can occur year-round and at all hours.

Be prepared

  • Watch for signs of approaching storms.
  • Check the weather forecast before heading outdoors for extended periods of time.
  • Postpone outdoor activities if thunderstorms are imminent. Avoid being caught in a dangerous situation.
  • If a storm is approaching, tune in to a NOAA weather radio, which picks up around-the-clock broadcasts from the National Weather Service.

Know what to do

  • Find safe shelter immediately inside a sturdy building, away from windows, doors and electrical appliances.
  • Avoid contact with conductors of electricity such as appliances, metal objects and water.
  • Get out of boats and away from water. Find a low spot away from trees, fences and poles that is not subject to flooding.
  • If you are in the woods, take shelter under the shorter trees. Squat low to the ground on the balls of your feet with your hands on your knees and your head between them. Make yourself the smallest target possible and minimize your contact with the ground.
  • Do not take a shower or bath.
  • Turn off air conditioners — power surges can overload the air conditioning equipment.
  • Telephone lines and metal pipes can conduct electricity. Avoid using the telephone or any electrical appliances; unplug all those unnecessary.

Stay informed

  • Severe thunderstorm watches tell you when and where severe thunderstorms are more likely to occur.
  • Severe thunderstorm warnings are issued when severe weather has been reported by spotters or indicated by radar.
  • Be aware of tornado and flash flood watches/warnings that can often be issued during severe thunderstorms.