30-30 Rule
When Thunder Roars, Go Indoors!

If you can hear thunder, you are close enough to the storm to be struck by lightning.  Lightning can strike as far away as 10 miles from the area where it is raining.

If you can see lightning flashes, count the seconds after a flash until you hear thunder.  If that time is 30 seconds or less, the storm is within 6 miles and is dangerous.  Seek shelter immediately.

Wait at least 30 minutes after the last clap of thunder before leaving shelter or resuming any indoor activity involving equipment that runs on electricity or contact with plumbing fixtures.

Don't be fooled by sunshine or blue sky!  Lightning is more likely to come from the back edge of a thundercloud than from the front edge.

Check out the Severe Weather Links for additional information.