During an electrical storm, you should avoid open water, plumbing, plugged-in electronics, open structures like gazebos, and anything that makes you the tallest object in an area. Lightning kills roughly 20 people per year in the United States and injures hundreds more, and most of those casualties come not from direct strikes but from ground current spreading outward from where lightning hits the earth.
Open Water and Swimming
Water is an excellent conductor of electricity. If lightning strikes a lake, pool, or ocean surface, the current spreads rapidly in all directions. Being in or even standing at the edge of a body of water during a thunderstorm puts you directly in that path. This applies equally to swimming pools, lakes, rivers, and the ocean. If you hear thunder or see lightning, get out of the water and move well away from the shoreline.
Plumbing and Running Water
Lightning can travel through a building’s plumbing, which means showers, baths, dishwashing, and even hand-washing carry real risk during a storm. Metal pipes conduct the current readily, but even homes with plastic plumbing aren’t fully safe because water itself is conductive. The CDC recommends avoiding all contact with plumbing and running water until the storm passes.
Plugged-In Electronics and Wired Devices
When lightning strikes a building or even the ground nearby, it can send a massive electrical surge through the wiring and into anything connected to an outlet. This surge can destroy sensitive components in computers, TVs, and other electronics, but more importantly, it can shock anyone touching a plugged-in device.
The safest approach is to unplug valuable devices before a storm arrives. If lightning is already striking nearby, don’t go near outlets to unplug anything. Just stay away from wired electronics entirely until the storm passes. Surge protectors offer some protection for your equipment, but they’re designed to handle smaller surges, not a direct or very close lightning strike.
Corded Phones vs. Cell Phones
Corded landline phones are directly wired into the building’s infrastructure and can carry a lightning surge straight to your ear. This is a well-documented cause of lightning injuries. Cell phones and cordless phones, by contrast, are safe to use during a storm. They have no physical connection to the building’s wiring. The Australian Lightning Protection Standard actually recommends using mobile phones instead of corded telephones during storms for exactly this reason.
Open Shelters and Exposed Structures
Picnic pavilions, gazebos, bus shelters, dugouts, and covered porches feel like protection, but they offer almost none. These open-sided structures don’t redirect electrical current the way a fully enclosed building does. Standing under one can actually increase your risk if lightning strikes the structure’s frame, because you become part of the path to ground. A safe shelter is a fully enclosed building with wiring and plumbing (which act as grounding paths) or a hard-topped metal vehicle.
Concrete Walls and Floors
Leaning against a concrete wall or lying flat on a concrete floor during a storm is riskier than most people realize. Concrete itself is a poor conductor, but the steel rebar embedded inside it is not. Those steel rods act as down conductors, carrying lightning current through the structure. If you’re in contact with a concrete wall or floor that has rebar running through it, you can become part of the circuit.
Convertibles, Golf Carts, and Open Vehicles
A regular car with a metal roof and frame is one of the safest places to be during a lightning storm, but not because of the rubber tires. Lightning travels miles through the air before reaching the ground; a few inches of rubber provides zero insulation. What actually protects you is the metal shell of the car acting as a Faraday cage, carrying the electrical current along the outer surface and into the ground without it reaching the interior.
This protection only works with fully enclosed metal vehicles. Convertibles, fiberglass-bodied cars, golf carts, open-cab tractors, riding mowers, and motorcycles don’t provide this shielding. If you’re on or in one of these when a storm approaches, abandon it and get to a safe enclosed building or a hard-topped metal vehicle.
Being the Tallest Object in an Area
Lightning tends to strike the tallest object in an area, so standing in an open field, on a hilltop, at the peak of a ridge, or on a rooftop dramatically increases your risk. Isolated tall trees are frequent strike targets, and standing under one puts you in danger from both a direct strike and the side flash that jumps from the tree to nearby objects. If you’re caught outdoors with no shelter available, move to the lowest ground you can find and crouch low. Avoid hilltops, ridgelines, and open fields where you’d be the highest point.
Ground Current and Standing Near Strike Points
Ground current is the leading cause of lightning casualties. When lightning hits the earth, the electrical current spreads outward along the surface. It enters your body at the point closest to the strike (typically one foot) and exits at the point farthest away (the other foot). The greater the distance between those two contact points, the greater the voltage difference across your body and the greater the potential for serious injury or death. This is why lying flat on the ground is actually more dangerous than crouching: it increases the span of your body in contact with the ground, giving the current a longer path through you.
Using the 30-30 Rule
The simplest way to know when to take shelter and when it’s safe to resume activities is the 30-30 rule from the National Weather Service. When you see lightning, count the seconds until you hear thunder. If it’s 30 seconds or less, the storm is close enough to be dangerous and you should get to shelter immediately. If you can’t see the lightning, hearing thunder at all means the storm is within striking distance. After the last flash of lightning, wait at least 30 minutes before going back outside. Many lightning injuries happen because people return to outdoor activities too soon after a storm seems to pass.