What you need to know
Lightning kills an average of 20 Americans every year and injures hundreds more, according to the National Weather Service. The single most important rule is simple: if you hear thunder, go inside immediately. Lightning can strike up to 10 miles away from rainfall, and if you can hear the storm, you're within striking distance.
The old "30-30 rule" — count seconds between lightning and thunder, seek shelter if it's under 30 — has been replaced by clearer guidance: don't wait to count. When thunder roars, go indoors.
Why lightning is more dangerous than most people think
Lightning doesn't have to hit you directly to kill you. Ground current — electricity spreading outward through the earth after a nearby strike — accounts for roughly half of all lightning fatalities, according to the National Weather Service. A bolt can strike a tree, fence, or open field and send current through the ground for dozens of yards in every direction.
Water, metal objects, and open terrain amplify the danger. That's why beaches, golf courses, and athletic fields are among the most dangerous places to be during a thunderstorm.
The National Oceanic and Atmospheric Administration (NOAA) reports that most lightning deaths occur during summer afternoons when people are outdoors for recreation. Florida, Texas, and other Gulf Coast states see the highest number of lightning fatalities, driven by frequent thunderstorms and year-round outdoor activity.
If you hear thunder, go inside — no math required
For decades, safety educators taught the 30-30 rule: if the time between seeing lightning and hearing thunder is less than 30 seconds, seek shelter and wait 30 minutes after the last thunder before resuming outdoor activities.
The National Weather Service has moved away from this guidance. The problem? It requires people to time the gap accurately, remember the formula, and act quickly — all while a storm is approaching. Worse, it implies that storms farther than six miles away are safe, which isn't true.
The modern rule is simpler and safer: if you can hear thunder, you're close enough to be struck. Lightning can and does strike more than 10 miles from the center of a storm. Bolts from the blue — strikes that appear to come from clear sky — can travel horizontally for miles before arcing to the ground.
The second half of the rule remains unchanged: wait at least 30 minutes after the last rumble of thunder before going back outside. Storms can linger, and many lightning injuries happen when people leave shelter too soon.
What counts as safe shelter?
Not all shelter is created equal. The National Weather Service defines safe shelter as either:
- A substantial building with four walls, a roof, and preferably plumbing and wiring. The metal in these systems helps conduct electricity safely into the ground if the building is struck. Homes, schools, offices, and shopping centers qualify.
- A fully enclosed metal vehicle with a hard top and the windows rolled up. Cars, trucks, vans, and buses are safe — not because of the rubber tires (a myth), but because the metal shell conducts electricity around the occupants and into the ground.
Not safe:
- Picnic shelters, dugouts, tents, or carports (open structures with no walls)
- Convertibles or vehicles with fiberglass/composite shells
- Under trees or near tall isolated objects
- In or on water
If you're inside a building during a storm, stay away from windows, corded phones, plumbing, and electrical appliances. Lightning can travel through wiring and pipes. Avoid taking a shower or washing dishes until the storm passes.
Are you safe in a car during a lightning storm?
Yes — as long as it's a hard-topped, fully enclosed metal vehicle.
The metal frame of a car acts as a Faraday cage, conducting the electrical charge around the outside of the vehicle and into the ground through the tires and undercarriage. This protects the occupants inside.
Important caveats:
- Keep your hands in your lap and avoid touching metal surfaces like door handles, the steering wheel, or the radio.
- Do not lean against the door.
- Keep windows closed.
- Pull over safely if visibility is poor, but do not exit the vehicle during the storm.
Convertibles, golf carts, motorcycles, bicycles, and riding lawnmowers offer no protection. If you're on one of these when a storm approaches, abandon it and seek a building or hard-topped vehicle immediately.
What if you're caught outside with no shelter?
This is a dangerous situation with no perfect solution. If you're caught in the open with no buildings or vehicles nearby:
- Get to low ground. Move away from hilltops, ridges, and open fields. Avoid being the tallest object in the area.
- Stay away from isolated tall objects like lone trees, flagpoles, or light posts. Lightning seeks the path of least resistance to the ground, and tall objects are often struck first.
- Avoid water and metal. Get out of lakes, pools, and oceans. Drop golf clubs, umbrellas, fishing rods, and backpacks with metal frames.
- Spread out if you're in a group. If one person is struck, others can call for help and provide first aid.
- Do not lie flat on the ground. This increases your contact with the ground and your exposure to ground current. Crouch low on the balls of your feet with your heels together, minimizing ground contact. This is a last resort, not a reliable safety measure.
The best strategy is to avoid being caught outside in the first place. Check the forecast before outdoor activities. If thunderstorms are in the forecast, have a plan to get indoors quickly.
Lightning and severe weather alerts
Lightning is a hazard in every thunderstorm, not just severe ones. A storm does not need to meet severe criteria to produce deadly lightning.
That said, the National Weather Service issues Severe Thunderstorm Warnings when storms produce large hail, damaging wind, or frequent lightning. Some warnings explicitly mention "frequent cloud to ground lightning" as a threat.
Wireless Emergency Alerts (WEA) for Severe Thunderstorm Warnings now reach most smartphones, breaking through Do Not Disturb mode by default. These alerts are geographically targeted and can give you critical minutes to get inside.
Third-party weather apps are silenced by Do Not Disturb, though Wireless Emergency Alerts for tornado and flash flood warnings still break through on most phones. For storms that develop quickly — especially in the Southeast or during overnight hours — having multiple alert methods can save your life.
First aid for lightning strike victims
If someone is struck by lightning, call 911 immediately. Lightning victims do not carry an electrical charge and are safe to touch.
Many lightning strike victims go into cardiac arrest. If the person is unresponsive and not breathing:
- Start CPR immediately. Push hard and fast in the center of the chest at a rate of 100-120 compressions per minute.
- Use an AED if available. Automated external defibrillators are often found in schools, parks, and public buildings.
- Continue until help arrives. People struck by lightning can often be revived with prompt CPR, even if they appear lifeless.
Lightning strike survivors may also suffer burns, broken bones, neurological damage, and hearing or vision loss. Even if the person seems okay, they need immediate medical evaluation.
The bottom line
You don't need to count seconds or calculate distances. The guidance is simple: when thunder roars, go indoors. Stay inside a substantial building or hard-topped vehicle until at least 30 minutes after the last thunder.
Most lightning deaths are preventable. The victims are often people who saw the storm coming but delayed seeking shelter — finishing a game, walking back from the beach, waiting under a tree. Don't be one of them.
VORTEX is a free web app at vortexintel.app that monitors severe weather nationwide. Pro ($4.99/month) places phone calls to your phone when a tornado or flash flood warning is issued for a location you care about — calls can ring through Do Not Disturb once you enable Emergency Bypass for the number, unlike most third-party app notifications.