What to do if you are caught in a thunderstorm while hiking or camping

1. How do you avoid getting within the lightning range?

Every year, hikers are struck by lightning. It often results in severe burns, cardiac arrest,  or even death. Direct lightning strikes are quite exceptional, but indirect lightning strikes and their consequences are to be taken very seriously. We will first see how to try not to find yourself exposed to lightning, then what to do if you find yourself in the vicinity of it. 

As always, prevention is better than cure. So how do you avoid getting within the lightning range?

By asking about the weather before leaving. You can do this on the internet or by phone and even contact locals (refuge guardians for example) – who know their area well and can predict the weather locally. It is something you should always do before going hiking. If the risks are too big, stay home, do something else or go somewhere else.

By leaving early. Thunderstorms occur more often late in the afternoon or the evening, especially during the summer months. You are therefore less likely to be exposed to thunderstorms if you leave early and return early or mid-afternoon. But be careful, it doesn’t guarantee you won’t have a storm at 10 am.

By looking up, spotting threatening clouds and following their progress. Even if you’re not a meteorologist, nothing is stopping you from watching the sky. Do this regularly, as it is possible that only half an hour may elapse between a beautiful blue sky and a storm. Thunderstorms can form very quickly – especially in the mountains in summer.

By anticipating. If there is a risk of a thunderstorm, do not enter an area particularly exposed to lightning (plateau, ridge, summit, etc.). Wait for the storm to pass through by staying in a less exposed area (valley, depression, etc.), turning around, or adapting your route.

By planning. If the weather is uncertain, always have a backup solution in mind and estimate how long it will take you to get to safety. It’s not when the storm is 1 km away that you have to start thinking about going back to the valley that is 4 hours walk away!

By knowing how to turn around. Turning around isn’t easy. We always tend to say to ourselves, “Maybe the storm will pass us by” and postpone the moment when we have to go the other way. The problem is that in the meantime, there is often no time to turn back to a haven. It’s hard to say that you might turn around for nothing, but is the risk of being struck by lightning worth going on?

By observing the animals. Although I have never personally seen it, it seems that animals especially cows come down from peaks and ridges when a storm approaches. So once again, observe what is around you – even if you are suffering, head down, in an endless climb.

Storms in Phong Nha, and who is deciding for you

Everything in this guide assumes the call is yours. On a guided trip it is not, and that is worth understanding before you book anywhere in central Vietnam, where the wet season runs roughly September to November and afternoon storms are ordinary rather than exceptional.

Our guides turn trips around. Phong Nha-Ke Bang is karst, so water that fell an hour ago upstream arrives in a dry stream bed with no warning from the sky above you, and a river crossing that was knee-deep on the way in is the reason people get stuck. A guide who says the word no on a morning that looks fine is doing the job.

Our Ma Da Valley Jungle Camping 2D1N is an overnight in that terrain, which means someone else is watching the weather while you sleep.

2. If you are in the range of lightning, you must take the following precautions

DO'S

Get to a building or a hard-topped vehicle if one is anywhere within reach. This is the only advice on this page that actually makes you safe. Everything below it is damage limitation for when no such thing exists, which in the middle of a national park is most of the time.

Get off the high ground. Height, a pointed shape and isolation are what decide where a bolt lands, according to the US National Weather Service. A ridge, a summit or an open plateau gives you all three. Drop into a valley or a depression, and check you are not dropping into something that floods.

Spread the group out, roughly 20 to 30 m apart. One strike then injures one person instead of all of you, and the rest of the group can carry them out. This is the single most useful thing a group can do and almost nobody does it.

Move away from water, and from wet rope and wet ground. Give a lake or a river a wide margin. Ground current travels, and it travels better through wet ground than dry.

Keep moving towards real shelter. Walk, do not run. If your hair stands on end or you hear buzzing, that is not a warning you can act on in time, but it does mean you should not be standing where you are.

Wait 30 minutes after the last thunder before you carry on. Not after the last flash, after the last sound. Lightning strikes more than three miles from the centre of a storm routinely, and bolts from the blue have hit 10 to 15 miles out, so a clear patch of sky above you means very little.

Two things this article used to tell you, which are wrong

Crouching does not help. Earlier versions of this page described the lightning crouch: on the balls of your feet, heels together, head on knees, sitting on your pack. It was taught for years. the US National Weather Service now states plainly that crouching does not make you any safer outdoors. It costs you the one thing that does help, which is time spent walking to shelter. We have removed it.

Metal does not attract lightning. The old advice was to throw your trekking poles and your pack 30 m away. The National Weather Service is direct about this: the presence of metal makes absolutely no difference to where lightning strikes. Do not stop to strip your kit off, and do not leave your pack behind in a storm in the tropics, because you will want the dry layer in it. Long conductors already fixed in the ground, like a wire fence or a pipeline, are a different case, and those are worth standing clear of.

DONT'S

Don’t panic. Many accidents happen in this way – hikers who panic and injure themselves by doing something careless (to be polite).

Don’t run. It would seem that lightning can pass through the current of air created behind you, but mainly because you risk injuring yourself by slipping or falling.

Do not stay on a high point like a ridge, a plateau, a summit… because lightning is more likely to strike in these places. Take shelter in a depression, valley or low point. In this case, be careful not to put yourself in an area that could get flooded quickly.

Do not shelter under an isolated tree or an isolated open shelter. If lightning strikes on a tree, it is the tree that will fall on you or you risk getting hit by a piece of burning tree. Also, lightning is more likely to strike at a high point. An isolated open shelter will also not protect you from lightning and will tend to attract it. If you are in a forest, move away from the tallest trees.

Do not shelter under a rock face. For the same reasons as the lonely tree, if lightning strikes the rocks, they may fall on you.

Do not stay near the void or steep slopes. Many accidents due to lightning are not due to the strike itself, but to a fall following it (people fell into the void, on a steep slope, on rocky walls…).

Do not shelter in a small cave or rocky cavity. It would seem this kind of “path” attracts that lightning.

3. If you are camping

A tent gives you no protection from lightning at all. Poles, aluminium or carbon, do not change that either way, and the fabric does nothing. The National Weather Service is explicit that a tent offers no protection.

So the decision is made when you pitch, not when the storm arrives. Camp low rather than on the shoulder of a hill. Stay out of the last few metres before a stream, which is where flash flooding takes tents. Keep away from the tallest tree in sight, and away from anything dead that is tall.

If a storm arrives in the night, the honest answer is that there is usually nothing useful to do at 2 am in a forest. Move the group's tents apart if they are clustered, stay off the wet ground where you can, and wait it out. Getting up and walking a ridge in the dark is worse.

4. Questions people actually ask

Is it safe to be in a forest during a thunderstorm? Safer than an open field or a ridge, and not safe. Being under a tree is the second leading cause of lightning casualties, so a forest is only better because it is not one tall isolated tree. In dense uniform forest, get away from the tallest trees and from any clearing edge, and keep moving out.

What do I do if I am caught hiking with no shelter anywhere? Get off the high ground, spread the group out, keep walking towards the nearest building, and stay away from water. Do not crouch, do not run, do not shelter under a lone tree, a rock face or in a shallow cave mouth.

How long do I wait before carrying on? Thirty minutes after the last thunder you hear.

Can it strike if the sky above me is clear? Yes. Bolts from the blue have struck 10 to 15 miles from the storm. Thunder is the signal, not rain.

Does my phone or my belt buckle attract it? No. Height, shape and isolation decide where it lands.

Knowing when storms are likely helps as much as knowing what to do in one. Our guide to Vietnam's rainy season sets out the months to plan around, region by region.