There are an estimated 25 million cloud-to-ground lightning flashes each year. While lightning can be fascinating to watch, it is also extremely dangerous.
During the past 30 years, lightning has killed an average of 66 Americans and injured another 300. The number of Americans killed by lightning typically exceeds the number of deaths resulting from both tornadoes and hurricanes.
Most lightning-caused deaths occur during the spring and summer months when the frequency of thunderstorms and outdoor activities peak. During the past 40 years, Texas ranked second in the country behind Florida in total number of lightning fatalities.
By definition, all thunderstorms produce lightning. During a thunderstorm, each flash of cloud-to-ground lightning is a potential killer. Although some victims are struck directly by the main visible lightning stroke, most are affected by nearby strikes as the current moves in and along the ground. Because of these indirect strikes, most victims survive, though often with lifelong painful effects. While virtually all people take some protective action during a thunderstorm, many unknowingly leave themselves vulnerable.
Lightning can strike as far as 10 miles away from the rain area in a thunderstorm, which is about the distance from a storm that you are able to hear the thunder. If you can hear the thunder then you are within striking distance of that storm. Also, when you can clearly hear thunder in an urban setting above the city noise, it is time to abandon outdoor activities.
Follow the 30/30 lightning safety rule when thunderstorms threaten your area. Go indoors if after seeing lightning you cannot count to 30 before hearing thunder. This method may be too difficult if lightning from an approaching storm is very frequent and thunder is nearly constant. Just head indoors. Then stay indoors for 30 minutes after hearing the last clap of thunder. Do not prematurely resume outdoor activities as the storm moves away. Following these guidelines will contribute greatly to your safety from the deadly beauty of lightning.
National Weather Service Lightning Safety