When does play have to stop because of lightning or thunder?

As soon as thunder is heard or lightning is seen. The NFHS lightning guidelines (October 2024) say that at that point, the leading edge of the storm is close enough to strike your location.

1. Suspend play for at least 30 minutes.
2. Clear the outdoor area immediately and move everyone to the designated safer place.

If you're monitoring a lightning detection network, also suspend play when lightning is detected within 10 miles, even before you hear or see it.

Don't wait for the rain. The National Weather Service says lightning often strikes outside the area of heavy rain, as far as 10 miles from any rainfall, and many lightning deaths happen ahead of storms because people wait too long to take shelter. Its rule of thumb: "When thunder roars, go indoors."