Storm Safety

Hiking/camping

Lightning risk increases dramatically for people on mountains or high up in hilly terrain, especially if you're both high up and exposed. Hiking can make lightning safety pretty tricky, because being exposed increases your chances of being struck, but taking shelter under trees increases the odds that you can be hit indirectly or by a ground current.

Taking shelter in a tent does not protect you from lightning. Nearby lightning strokes can create strong ground currents, which are a significant danger even if you're not struck directly. This ground current can kill you just as surely as a direct lightning hit.

If you're caught in the open while camping or hiking, finding safe shelter can be difficult. Your best bet is to take shelter inside a vehicle, where you'll be protected from lightning strikes. A better idea, though, is to plan ahead. Be aware of the weather in your area; if a storm approaches, give yourself time to reach shelter. Plan out trips in advance, and be aware of forecasts of thunderstorm activity.

Keep in mind that hiking in mountainous terrain may expose you to the risk of lightning activity long before you're aware of it. Rugged terrain can block the sound of thunder until a storm is right on top of you, and storms may develop directly overhead. At high altitude, the earliest part of a rainstorm may not reach the ground before it evaporates, so a thunderstorm can be in your area without you even being aware of it. Do not rely on hearing thunder before you make a decision to seek shelter!

Remember too that there is no safe place to be in the mountains. According to the NOAA, hikers and campers have been killed by lightning even inside caves.

Boating

A boat is one of the worst possible places to be during a thunderstorm. Lightning finds an easy path to ground through the radio equipment or masts of a boat. A boat often makes for the easiest and most accessible point of charge accumulation during a thunderstorm; in fact, during the days of wooden sailing ships, sailors would sometimes report a blue coronal discharge, which they termed "St. Elmo's Fire," around the masts of ships. The discharge is caused by the formation of plasma around the highest elements of the ship.

Being in a ship during a thunderstorm is a lot like sitting at the base of a lightning rod. The only good protection for people boating in a thunderstorm is to get off the water. All other things being equal, large metal-hulled vessels are safer than small fiberglass-hulled vessels, and some vessels are fitted with lightning protection systems. These are usually a combination of a lightning rod coupled to large metal plates in contact with the water, and serve to draw the electrical current to ground as quickly as possible.

However, there is no such thing as a "safe" boat during a thunderstorm. Some boats are safer than others, but no boat is entirely safe. Because thunder can usually be heard only for about five miles or so, even on open water, and lightning can strike eight miles from the leading edge of a cloud, do not rely on hearing thunder to gauge when it's necessary to return to shore!

The CDC offers a boating lightning protection page.

Sports

It's better to be wet than dead.

Outdoor sports are, according to some statistics, the fastest-growing category of activities resulting in lightning injury and death. Referees and organizers are often reluctant to cancel games, especially if tit's not raining and there's no audible thunder, so many times outdoor sporting events will continue even when the threat of lightning strikes is imminent.

People trapped outdoors during a thunderstorm may try to seek shelter from the rain beneath metal bleachers or trees. However, these are among the worst places to be during a thunderstorm! In situations where you're caught outdoors during a thunderstorm, seek safe shelter in a car or large building. Avoid trees, bleachers, metal sheds, and similar structures; if you have no other choice, crouch on the ground in a ball with as little contact with the ground as possible.

Sporting organizations should always designate at least one "lightning safety officer"–a person whose job it is to monitor the weather and be aware of approaching thunderstorms. This person should have the authority to call off a game without question, even if the coaches or referees do not hear thunder. It's important not to wait until the last minute before calling a game; people need enough time to seek safe shelter.

Swimming

Many of the same concerns that are true of boating are especially true of swimming. When i said that being in a boat during a thunderstorm is a worst-case scenario, I lied; swimming outdoors during a thunderstorm is even worse, and swimming outside in salt water during a thunderstorm is worse still. The only safe thing to do if you're swimming outdoors and a thunderstorm forms is to get out of the water.

But even indoor pools are not safe during a thunderstorm. Lightning can create massive ground currents which can travel through the ground for considerable distances from where the bolt hits. These ground currents can be an electrocution hazard even if you're in an indoor pool. If there's lightning around, don't go swimming.