Lightning Safety: What the 30-30 Rule Got Right, and What NWS Changed

Lightning kills an average of 20 people in the United States each year and injures hundreds more. Most lightning deaths occur when people are caught outside and don't seek shelter quickly enough. The good news is that lightning fatalities are almost entirely preventable if you understand the risks and follow simple safety guidelines.

This guide covers what the 30-30 rule got right and the part NWS has since replaced, explains where to seek shelter during thunderstorms, and outlines what to do (and not do) when you're indoors during electrical storms.

The 30-30 Rule, and What Replaced Its First Half

The 30-30 rule has two halves. The second still stands. The first has been replaced, and it is worth knowing why.

First 30: replaced by "When Thunder Roars, Go Indoors"

The original rule told you to count the seconds between the flash and the thunder and to seek shelter if the count reached 30 seconds or less. Sound travels roughly one mile every five seconds, so 30 seconds put the strike within about 6 miles.

The problem is what a longer count implies. A 40-second count is not permission to keep playing. Lightning can strike 10 or more miles from the parent storm, and a "bolt from the blue" can travel horizontally and hit ground under an apparently clear sky. Counting also takes time you may not have, and delay is what NWS names as the cause of most lightning deaths.

So the current NWS trigger is unconditional and needs no stopwatch: if you can hear thunder, you are within striking distance. Go indoors. Flash-to-bang counting is still useful, but as a gauge of how far away the storm is, never as permission to stay outside.

Second 30: When it's safe to resume activities

Wait 30 minutes after the last thunder you hear before leaving shelter. Many lightning casualties occur just before or after a storm, when people either haven't sought shelter yet or venture out too soon. Thunderstorms can produce dangerous lightning throughout their entire lifecycle, not just during the heaviest rain.

Updated, the framework is simpler than the original: shelter at the first thunder you hear, and stay sheltered for 30 minutes after the last one.

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Where to Find Safe Shelter

Not all shelter is equally protective during thunderstorms. Understanding what makes a shelter safe can save your life.

Best shelter: Substantial buildings

A fully enclosed building with wiring and plumbing provides the best protection from lightning. This includes homes, schools, offices, shopping centers, and similar structures. The building's electrical wiring and plumbing create multiple paths for lightning current to flow to the ground if the structure is struck.

Inside a building, you're protected by the electrical infrastructure, not the walls themselves. Open structures like picnic pavilions, dugouts, gazebos, and bus shelters do not provide adequate protection because they lack the wiring and plumbing that would conduct lightning safely to ground.

Second best: Hard-topped vehicles

A car, truck, van, or other hard-topped metal vehicle with the windows rolled up provides good protection, but not for the reason most people think. The rubber tires are not what protects you. At the voltages lightning produces (up to 300 million volts), rubber provides negligible insulation.

Instead, a vehicle protects you through the Faraday cage effect. The metal frame of the vehicle conducts lightning current around the outside and down to the ground, keeping the interior safe. To maximize protection:

• Keep windows completely closed
• Don't touch metal surfaces inside the vehicle
• Pull over and wait out the storm rather than driving

Convertibles, motorcycles, bicycles, and open-cab vehicles do not provide lightning protection.

Unsafe locations to avoid

During thunderstorms, stay away from:

• Open fields, parks, and golf courses, Being the tallest object in an open area dramatically increases your risk
• Under isolated trees, Lightning frequently strikes the tallest object, and current can jump from a tree to nearby people
• Near water, Lakes, pools, beaches, and wet areas conduct electricity and should be evacuated immediately when storms approach
• Hilltops and ridgelines, Elevation increases exposure
• Open vehicles, Golf carts, tractors, boats, and convertibles offer no protection
• Bleachers and metal fences, Metal conducts lightning current long distances
• Tall isolated structures, Flag poles, light towers, and scaffolding

Indoor Lightning Safety

Being inside a building doesn't mean you can ignore the storm. Lightning can affect you indoors in several ways.

Stay away from plumbing

Water conducts electricity, and metal pipes can carry lightning current throughout a building. During thunderstorms:

• Don't shower or bathe
• Don't wash dishes
• Don't do laundry
• Stay away from sinks and faucets

While the risk of serious injury from lightning conducted through plumbing is low, it's not zero. Wait until the storm passes to use water.

Avoid corded electronics

Lightning can travel through electrical wiring into your home. During storms:

• Don't use corded phones (cell phones are safe)
• Do not unplug equipment during a thunderstorm
• Stay away from outlets and electrical equipment
• Don't touch electrical cords or plug things in during the storm

If you want to unplug sensitive electronics, do so before the storm arrives. Typical surge protectors do not protect equipment from a lightning strike. See the NWS indoor lightning guidance.

Battery-powered laptops, tablets, and cell phones can be used indoors when they are disconnected from chargers and other household wiring.

Stay away from windows and exterior doors

While glass itself doesn't attract lightning, windows and doors can admit dangerous side flashes if lightning strikes nearby. The concussion from a very close strike can also shatter windows. Stay in interior rooms away from windows during the most intense part of the storm.

Concrete floors and walls

Concrete often contains metal rebar or wire mesh for reinforcement. This metal can conduct lightning current. During storms, avoid lying on concrete floors or leaning against concrete walls, especially in basements and garages.

Caught Outside with No Shelter

There is no safe place outdoors in a thunderstorm. That is the starting point, and it is worth being blunt about it: nothing in this section makes you safe. These are last-resort steps to shave a little risk off a situation you should never have been in, which is why the real answer is always to reach a substantial building or a hard-topped metal vehicle before the storm arrives.

A note on the crouch: for years the standard advice was to squat on the balls of your feet with your heels together. The National Weather Service dropped that recommendation. It offers no meaningful protection, and the false sense of security it created was doing more harm than the posture ever prevented. Don't waste time on it. Spend that time getting to shelter.

If you are genuinely stuck outside with nowhere to go:

Keep moving toward real shelter. A building with wiring and plumbing, or a hard-topped vehicle with the windows up, is the only meaningful protection. Keep heading for one rather than settling in place.

Separate from others. If you're with a group, spread out while continuing toward shelter. If lightning strikes and injures one person, others can provide help.

Keep moving to shelter. Do not delay to remove metal items or take off a backpack. Metal does not attract lightning, but it conducts current, so avoid fences, railings, and bleachers. The NWS lightning myths guidance explicitly warns against wasting time removing metal.

Avoid elevated and exposed positions. Get off hilltops, ridges, and open ground. Move away from isolated tall trees, and never shelter under one. Avoid low-lying areas that might flood.

If your hair stands on end or you hear crackling or buzzing, a strike may be imminent, but treat that as a sign you are already in serious danger rather than as a cue to adopt a posture. There is no position that reliably protects you. Keep moving toward a building or vehicle.

Lightning Myths Debunked

Several dangerous myths about lightning persist. Understanding the truth can help you make better decisions.

Myth: Lightning never strikes the same place twice. Reality: Lightning regularly strikes the same location multiple times, especially tall structures. Tall buildings can be struck repeatedly within a single storm.

Myth: Rubber tires protect you in a car. Reality: It's the metal frame creating a Faraday cage, not the rubber tires. At lightning voltages, rubber provides no meaningful insulation.

Myth: If someone is struck by lightning, don't touch them, they're electrified. Reality: The human body doesn't store electrical charge. Lightning victims are safe to touch and need immediate medical attention. Check that you can approach safely, call 911, and begin CPR if the person is unresponsive and is not breathing normally or is only gasping.

Myth: Metal attracts lightning. Reality: Lightning strikes based on height, shape, and isolation, not the presence of metal. Wearing jewelry or a metal belt won't make you more likely to be struck. However, metal conducts current, so after lightning strikes, metal objects can burn you.

Myth: If it's not raining, you're safe. Reality: Lightning can strike several miles from the rain shaft. "Bolts from the blue" can travel horizontally from storm clouds and strike in areas with clear sky overhead.

When Lightning Strikes: First Aid

If someone near you is struck by lightning, first check that you can approach safely:

1. Call 911 immediately. Lightning strikes are medical emergencies.

2. It's safe to touch the victim. They carry no electrical charge.

3. Begin CPR if needed. If the person is unresponsive and is not breathing normally or is only gasping, begin CPR, starting with chest compressions. Lay rescuers should not delay CPR to check for a pulse. Follow the 911 dispatcher's instructions, give rescue breaths if trained and able, and use an AED as soon as one is available, following its prompts. See the American Red Cross CPR steps.

4. Check for burns. Look for entry and exit wounds, lightning often enters through the head or upper body and exits through the feet.

5. Watch for shock. Even if the person is conscious, they may go into shock. Keep them calm and lying down until help arrives.

6. Don't move them unless there's immediate danger of additional lightning strikes.

Planning Ahead

The best lightning safety is avoiding exposure in the first place.

Check the forecast. Before outdoor activities, check for thunderstorm chances. Weather apps like WeatherAI provide hour-by-hour forecasts and severe weather alerts.

Have an escape plan. Know where you'll go if storms develop. Identify substantial buildings and vehicles you can reach quickly.

Monitor conditions. Watch the sky for developing storms. Towering cumulus clouds indicate growing instability. Dark, anvil-shaped clouds indicate mature thunderstorms.

Set time limits. If storms are forecast for late afternoon, plan outdoor activities for morning. Don't push your luck by staying out "just a little longer."

Use lightning data as context. WeatherAI offers nearby lightning data with Standard or Pro and GLM lightning imagery with Pro. Coverage and timestamps depend on the product. Do not wait for an app indication before sheltering when you hear thunder.

The Bottom Line

Lightning is one of nature's most dangerous phenomena, but it's also one of the most preventable weather-related causes of death. The rule worth carrying is shorter than the original: go inside at the first sound of thunder, and stay sheltered for 30 minutes after the last one.

Safe shelter means a substantial building with wiring and plumbing, or a hard-topped metal vehicle with windows closed. Open structures, trees, and bodies of water are dangerous during lightning storms.

Inside, avoid plumbing and corded electronics. Outside with no shelter available, there is no posture that protects you, so keep moving toward a building or a hard-topped vehicle and avoid being the tallest object in the area.

With modern weather tracking apps and radar, you have the tools to stay ahead of dangerous storms. Check the forecast, monitor conditions, and don't hesitate to seek shelter when thunder rumbles. Your life is worth more than finishing that round of golf or staying at the beach a little longer.

Stay safe out there.

Sources

• NWS on the lightning crouch, which it no longer recommends
• NWS lightning safety for the shelter and 30-30 guidance
• NWS lightning myths