YMCA of the USA and the National Lightning and Safety Institute recommend that both outdoor and indoor pools be cleared during a lightning and thunderstorm. We follow the 30-minute rule at all of YMCA of Greater San Antonio pools.

That means all Y pools (indoor and outdoor) close for 30 minutes after the last clap of thunder, or sight of lightning within a 12 mile radius of the pool. Members and guests must move off the pool deck to wait out a delay.

Why do we close our indoor pools during a storm?
Water is an excellent conductor of electricity. Just because a pool is surrounded by a structure does not make it safe during a storm.


  • Lightning kills more people in the U.S. than hurricanes and tornados combined.
  • The average storm is 6 - 10 miles wide and moves at 25 MPH.
  • 13 percent of all lightning incidents involve swimming, boating or fishing.
  • Thunder is usually heard up to 12 miles from a lightning strike. In other words, if you can hear thunder, you’re in danger of lightning.
  • Lightning strikes can reach up to 10 miles.  

That's why we follow the National Weather Service motto: When Thunder Roars, Go Indoors.