Lightning Safety

[Information taken directly from the Colorado Lightning Resource Center of the National Weather Service web page]

Safe Locations During a Lightning Storm

No place is absolutely safe from lightning! However, some places are much safer than others.

Safe locations include large enclosed structures and enclosed vehicles. A large enclosed structure is typically a building which is occupied by people on a permanent bases, such as a shopping center, schools, office buildings or a private residence. Once in a sturdy building, stay away from metal objects (faucets, showers, pipes) and phones, unless it is an emergency (cordless phones and battery operated cell phones are safe). Computers now a days are also dangerous as phone lines are usually connected to them.

Not all types of buildings or vehicles are safe during thunderstorms. Examples of buildings which are NOT safe (even if they are "grounded") include beach shacks, small metal sheds, picnic shelters, baseball dugouts etc. In general, buildings which are NOT safe have exposed openings such as those mentioned above. Vehicles such as automobiles, vans, school buses, etc. offer excellent protection from lightning, however, vehicles which are NOT safe during lightning storms are convertibles. Convertibles offer no safety from lightning, even if the top is "up". Other vehicles which are not safe during lighting storms are vehicles which have "open" cabs, such as golf carts, open cab tractors/construction equipment, etc.

Lightning Safety Plan of Action

The key to a lightning safety plan of action is knowing the answer to the following two questions: 1) how far away am I (or the group who I am responsible for) from a safe location? and, 2) How long will it take me (and/or my group) to get to the safe location? These questions need to be answered before lightning storms threaten. By knowing the answer to the above questions will greatly increase your chances of not becoming a lightning strike victim.

The "30/30" Lightning Safety Rule

There are 2 things to remember about lightning safety. First, how close should you let the lightning get to you before implementing your lightning safety plan of action, and second; how much time should elapse before resuming outdoor activities?

To estimate the distance between you and a lightning flash, use the "Flash to Bang" method: If you observe lightning, count the number of seconds until you hear thunder. Divide the number of seconds by five (5) to get the distance (in miles) the lightning is away from you.

Example:
If you see lightning and it takes 10 seconds before you hear the thunder, then the lightning is 2 miles away from you (10 divided by 5 = 2 miles).

If Thunder is heard...	The Lightning is...
5 seconds after a Flash	1 mile away
10 seconds after a Flash	2 miles away
15 seconds after a Flash	3 miles away
20 seconds after a Flash	4 miles away
25 seconds after a Flash	5 miles away
30 seconds after a Flash	6 miles away
35 seconds after a Flash	7 miles away
40 seconds after a Flash	8 miles away

It is recommended that you should begin to seek shelter if the time between the lightning flash and the rumble of thunder is 30 seconds or less.

You should not resume activities until after 30 minutes after the last audible thunder.

The combination of 1 and 2 above is known as the 30/30 Lightning Rule.

One thing to remember: Sometimes lightning storms can develop overhead. This means that the first lightning strike from the cloud might be in your immediate location. It is recommended that you should be alert for developing thunderclouds overhead when outdoors. If you see thunderclouds developing, you should implement your lightning safety plan of action.

For More Information

Visit the Colorado Lightning Resource Center for more information on lightning including:

Safety guidelines
First aid for lightning strike victims
What to do if you are caught in the open during a lightning storm

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