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Lightning and Thunderstorm Policy

It’s a common situation – a thunderstorm is approaching or nearby. Are conditions safe, or is it time to head for safety? Not wanting to appear overly cautious, many people wait far too long before reacting to this potentially deadly weather threat.

In order to understand the lightning threat, some basic information should be known. Thunderstorms produce two types of lightning flashes, ‘negative’ and ‘positive.’ While both types are deadly, the characteristics of the two types of flashes are quite different.
  • Of the two, negative flashes occur more frequently, usually under or near the base of the thunderstorm where rain is falling.
  • In contrast, positive flashes generally occur away from the center of the storm and often in areas where rain is not falling. Because these positive flashes occur where the lightning threat is perceived to be low or nonexistent, they often catch people by surprise.
Lightning is the result of the build-up and discharge of electrical energy, and this rapid heating of the air produces the shock wave that results in thunder, 25 million cloud-to-ground lightning strikes occur in the United States each year. Lightning often strikes as far as 10 to 15 miles away from any rainfall with each spark of lightning reaching over 5 miles in length and temperatures of approximately 50,000° F. Even if the sky looks blue and clear, be cautious. One ground lightning strike can contain 100 million volts of electricity. The National Lightning Safety Institute recommends waiting 30 minutes after the last lightning sighting or sound of thunder before resuming activities. Source: National Weather Service Web at

When thunder or lightning occur the Lifeguard Staff at the Walpole Public Pools have been instructed to:

  • Clear everyone from the water at the first sound of thunder or first sight of lightning. If you are in an elevated station, get down immediately.
  • Move everyone to a safe area free from contact with water, plumbing or electrical circuits. For outdoor facilities, move everyone inside, if possible. Large buildings are safer than smaller or open structures, such as picnic shelters or gazebos.
  • Keep patrons and staff out of showers and locker rooms during a thunderstorm as water and metal can conduct electricity.
  • Do not use a telephone connected to a landline except in an emergency.
  • Keep everyone away from windows and metal objects (e.g., doorframes, lockers).
  • Watch for more storms and monitor weather reports on a radio or TV broadcast, weather radio or
  • Keep away from tall trees standing alone and any tall structures.
  • Keep away from water and metal objects, such as metal fences, tanks, rails and pipes.
  • If you are outside of a building, keep as low to the ground as possible: squat or crouch with the
    knees drawn up, both feet together and hands off the ground. Do Not lie Flat on the ground.
  • Wait 30 minutes from the last clap of thunder or flash of lightning before allowing patrons to continue to use the facility.

Our Policy is based on training from the American Red Cross and the recommendations of NOAA and the USA Lifeguard Association for lightning safety.

Other Articles of interest printed from NOAA and the United States Lifeguarding Association for lightning safety: