Be Aware of Thunderstorm Hazards: Severe thunderstorms can produce dangerous winds, hail, and lightning. In addition, they can cause flash flooding in rivers and streams, dry gulches, and in low-lying places in cities and towns.
If You Can Hear It, Clear It, If You Can See It, Flee It: This saying means that you should take shelter if the time between a lightning flash and the thunder is 30 seconds or less, which means that the lightning is about 5 miles away. (To determine the distance, count the seconds between the flash and the thunder and divide by 5.) The safest shelters are indoors or in a vehicle. Lightning can strike 5-10 miles ahead of the storm, so don’t wait until the lightning is upon you to go inside. Don’t resume activities until 30 minutes after you hear the last thunder.
Indoor Lightning Safety: Stay away from windows, electrical equipment, and metal objects. Don’t take a bath or shower and don’t use the phone. Turn off unnecessary electrical equipment (such as TVs, computers, and air conditioners).
Outdoor Lightning Safety: Seek shelter indoors or in a car. Stay away from single tall objects (such as a tree) and metal objects (fences, pipes, rails). Don’t hold golf clubs, fishing poles. Remove backpacks with metal frames. It is not safe to be riding bicycles, motor scooters, motorcycles, or golf carts. If you are out in the open and cannot get to shelter, stand in a low spot under a group of trees (not under a lone tree) or crouch down on the balls of your feet—do not lie flat on the ground. If you are swimming or boating, get out of the water.