Thunderstorms may occur singly, in clusters or in lines. Thus, it is possible for several thunderstorms to affect one location in the course of a few hours. Thunderstorms can bring heavy rains (which can cause flash flooding), strong winds, hail, lightning and tornadoes. Some of the most severe weather occurs when a single thunderstorm affects one location for an extended time.

In a severe thunderstorm get inside a sturdy building and stay tuned to a battery-operated radio for weather information.

While thunderstorms and lightning can be found throughout the United States, they are most likely to occur in the central and southern states. Lightning is a major threat during a thunderstorm. In the United States, between 75 to 100 Americans are hit and killed each year by lightning. If you are caught outdoors, avoid natural lightning rods such as tall, isolated trees in an open area or the top of a hill and metal objects such as wire fences, golf clubs and metal tools.

It is a myth that lightning never strikes twice in the same place. In fact, lightning will strike several times in the same place in the course of one discharge.

The state with the highest number of thunderstorm days is Florida.