In the United States, there are an estimated 25 million lightning flashes each year. During the past 30 years, lightning killed an average of 66 people per year . This is more than the average of 65 deaths per year caused by tornadoes. Yet because lightning usually claims only one or two victims at a time and does not cause mass destruction of property, it is underrated as a risk. While documented lightning injuries in the United States average about 300 per year, undocumented injuries likely much higher.

Watch for Developing Thunderstorms: Thunderstorms are most likely to develop on spring or summer days but can occur year round. As the sun heats the air, pockets of warmer air start to rise and cumulus clouds form. Continued heating can cause these clouds to grow vertically into towering cumulus clouds, often the first sign of a developing thunderstorm.

An Approaching Thunderstorm: When to Seek Safe Shelter: Lightning can strike as far as 10 miles from area where it is raining. That's about the distance you can hear thunder. If you can hear thunder, you are within striking distance. Seek safe shelter immediately.

Use the 30-30 rule: where visibility is good and there is nothing obstructing your view of the thunderstorm. When you see lightning, count the seconds until you hear thunder. If that time is 30 seconds or less, the thunderstorm is within 6 miles and is dangerous. Seek shelter immediately. The threat of lightning continues for much longer than most people realize. Wait at least 30 minutes after the last clap of thunder before leaving shelter. Don't be fooled by sunshine or blue sky! If it is cloudy or objects such as building or mountains are obscuring your vision, get inside immediately. It is always safer to take precautions than to wait.

Outdoor Activities: Minimize the Risk of Being Struck: Most lightning deaths and injuries occur in the summer. Where organized outdoor sports activities take place, coaches, camp counselors and other adults must stop activities at the first roar of thunder to ensure everyone time to get a large building or enclosed vehicle. Leaders of outdoors events should have a written plan that all staff are aware of and enforce.

Indoor Activities: Things to Avoid: Inside building, stay off corded phones, computers and other electrical equipment that put you in direct contact with electricity or plumbing. Buy ground fault protectors for key equipment. Follow the 30-30 rule and stop activities at the first clap thunder and wait 30 minutes until after the last thunder strike.

Helping a Lightning Strike Victim: If a person is struck by lightning, call 911 and get medical care immediately. Cardiac arrest and irregularities, burns, and nerve damage are common in cases where people are struck by lightning. However, with proper treatment, including CPR if necessary, most victims survive a lightning strike. You are in no danger helping a lightning victim. The charge will not affect you.

Summary: Lightning is dangerous. With common sense, you can greatly increase your safety and the safety of those you are with. At the first clap of thunder, go a large building or fully enclosed vehicle and wait 30 minutes after the last clap of thunder to back outside.