A warm, humid afternoon in July. The sky over the housing estate turns the colour of wet slate, the first fat raindrops hit the patio, and ten seconds later the whole street flinches at a crack of thunder. British thunderstorms are often brief, local and easy to shrug off. They are also capable of putting a lightning strike into a golf course, a hilltop or a back garden with no warning at all.
Most of what keeps you safe is simple and free. Get inside a solid building or a hard-topped car, stay away from the things that conduct electricity, and wait until the storm has genuinely passed rather than until the rain stops. The UK records hundreds of thousands of lightning strikes in a typical year, and while fatalities are rare, injuries and near-misses are not. Here are the rules that matter, at home, in the open, in vehicles and at events.
What UK thunderstorms actually look like
Thunderstorms here tend to arrive in one of two ways. In spring and summer, warm humid air builds through the day and storms break out overhead in the afternoon or evening, sometimes as scattered cells and sometimes as a line of them marching across a county. At any time of year, a cold front can bring a short, sharp burst along a squall line, with a sudden drop in temperature and gusts that bring down branches.
Two things catch people out. First, lightning can strike several miles from the heaviest rain, so a storm that looks as though it is passing to your left can still reach you. Second, storms can develop overhead faster than a forecast refresh; a cloudless lunchtime is no guarantee of a cloudless three o'clock. Some summer outbreaks produce tens of thousands of strikes in a few hours, turning a quiet afternoon into a county-wide emergency.
The Met Office issues thunderstorm warnings, graded yellow, amber and red. They are worth checking in the morning if you have plans outdoors. Treat an amber warning as a reason to change those plans rather than to carry on and hope.
If you can hear thunder, you are close enough to be struck. There is no safe place outdoors in a thunderstorm.
Staying safe indoors
A house or flat is by far the best place to be. You are not completely immune, though: a strike on the building, an aerial or a nearby cable can travel along wiring, pipework and phone lines. A direct strike is rare, but indirect effects are common. A strike on a nearby power line can send a surge through your home's wiring, damaging electronics and giving you a shock if you are touching a plugged-in device.
Five things to do when thunder starts
- Move to an inner room, away from windows, doors and exterior walls.
- Unplug the television, router, computer, games console and anything else with a mains lead or an aerial connection. Surge protectors help; unplugging is better.
- Stay off corded phones and away from running water. No shower, no bath, no washing up. Plumbing and bathroom fittings conduct.
- Keep clear of radiators, pipes, metal door frames and metal window frames.
- Bring pets inside. A kennel, run or garden cat shelter is not protection.
Mobile phones are fine, but charging them during a storm is not ideal. Charge beforehand and keep a torch to hand in case the power goes. If you must make a call, use a mobile rather than a corded landline; cordless phones are also safer than corded models. If you do lose power, unplug sensitive equipment so it isn't hit when the supply returns, and have anything electrical that has taken a knock checked by a qualified electrician before using it again. In a high-rise flat, you are generally safe, but stay away from windows and balconies.
Caught outdoors with no shelter
If you are outside when a storm arrives, the priority is a substantial building or a hard-topped car. If neither is within reach, reduce your risk as you move towards one.
The 30/30 rule
Count the seconds between the flash and the thunder. Thirty seconds or less means the storm is close enough to strike where you are: get to shelter now. At 10 seconds, the storm is within about two miles—dangerously close. Once inside, stay there for 30 minutes after the last clap of thunder. The rain stopping proves nothing.
If you are caught in the open with nowhere to go:
- Crouch low with your feet together and your hands on your knees. Do not lie flat; that increases your contact with the ground and the current that can flow through it.
- Move off ridges, hilltops and open beaches, and away from isolated trees, tall poles, wire fences and metal gates.
- Get out of the water, whether that's the sea, a river, a lake or a pool, and head ashore if you are in a boat. Water carries current remarkably well.
- Put down golf clubs, fishing rods and metal-shafted umbrellas. Stop cycling, mowing or working with long metal tools.
- If you are in a group, spread out a few metres so one strike cannot affect everyone at once.
- If your hair stands on end or your skin tingles, a strike is imminent: crouch immediately and cover your ears to protect against thunderclap injury.
Standing under the only tree in a field is one of the worst choices available, and a wooden or glass bus shelter offers little protection because it lacks a metal shell to divert current. A metal bus shelter, if you are not touching the sides, is slightly better, but a building is far safer. Keep moving towards something solid.
Cars, caravans, tents and bikes
A hard-topped car with a metal body gives good protection, because the metal shell carries the current around you rather than through you. Close the windows, keep your hands off the door frames, and avoid touching any metal parts. Pull over safely if you are driving, turn on hazard lights, and wait out the storm. Do not park under trees or near power lines.
Convertibles with soft tops, fibreglass-bodied cars, motorcycles, bicycles and tractors offer little or no protection. If you are on a bike or motorcycle, stop, get off, and crouch away from the machine. Caravans and motorhomes with metal sides can provide some protection, but tents and awnings do not. If you are camping, move to the main building on site or a hard-topped vehicle. Avoid touching tent poles, which can conduct current. A golf buggy or a ride-on mower is no safer than standing in the open.
Before the storm: simple preparation
A few minutes of preparation can prevent a power cut from becoming a crisis. Keep a small emergency kit: torch, batteries, bottled water, and a battery-powered radio. Then run through these checks:
- Check the Met Office forecast and warnings in the morning if you have outdoor plans.
- Charge phones, power banks and torches.
- Secure garden furniture, trampolines and bins so gusts do not turn them into projectiles.
- Know where your fuse box is and how to reset it safely.
- If you have a vulnerable neighbour, check on them before and after the storm.
If someone is struck by lightning
A lightning strike can stop the heart or breathing. The human body does not store electricity, so it is safe to touch the victim. Call 999 immediately. If they are not breathing, start CPR and use a defibrillator if one is available. If they are breathing but unconscious, place them in the recovery position and keep them warm. Even if they seem fine, they should be checked by a medical professional, because effects such as confusion, hearing loss, burns and heart rhythm problems can appear later. Do not be afraid to help. Your actions can save a life.
Thunderstorms are part of British weather, but they do not have to be dangerous. Respect the 30/30 rule, get inside, and wait. The storm will pass; your safety is worth the pause.
Photo: 51581 / Pixabay
