What to do if you Get Caught in a Thunderstorm on a Mountain

lightning strike on a mountain
Getting caught in a thunderstorm on a mountain puts you at much greater risk of being struck by lightning than if you were at ground level. So what do you do if you get caught in a thunderstorm on a mountain as a hiker?

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I can cope with rain when hiking. I can even cope with wind (though I much prefer not to be blown off my feet). I can deal with ice courtesy of crampons. I can deal with the cold.

But one thing that utterly terrifies me (possibly beyond rational fear if I am being completely honest) is the prospect of being caught on a mountain in a thunder and lightning storm.

The fear is there for good reason:

  • Factlightning usually strikes the highest object in the area of the strike. So if you’re on a mountain summit and exposed, that object might be you
  • Fact: Lightning is hotter than the surface of the sun. So nobody wants to get hit by that! 

A hiker on a mountain in Scotland was killed by a lightning strike as recently as 2019. And on average in the UK, 2 people are killed by lightning each year. So it’s incredibly rare but something to be aware of particularly for those of us spending time on mountains.

In September last year I took on a wonderful scrambling route in the UK called Crib Lem Spur.

I had been indecisive about going because there had been a thunderstorm forecast for much of the area, but then closer to the day, the forecast changed and the specific area in which Crib Lem sits (the Carneddau) was forecast to be storm free. So I headed out.

It was a very hot September day and as I approached the bulk of the steep ascent towards the ridge (already a few km in), the clouds started to look a little ominous. Knowing thunderstorms were forecast elsewhere in North Wales that day I checked the weather again. And again. I was pleased to still have phone signal at this point.

All forecasts were confident that my route would be clear of thunderstorms so I proceeded and indeed the weather worked out well. 

But for a while I stopped and considered turning back. And had there been any hint whatsoever in the forecast of thunderstorms or had even one of the several forecasts I checked hinted at it, I’d have gone back.

Anyway, it worked out well… but it did get me pondering what I would actually do if I found myself in a thunderstorm on a mountain. So I went and found out. 

The Obvious: Try NOT to Get Caught in One

Weather forecasts are a hiker’s best friend. Check it a few days in advance when you make your plans, sure. But then check it again the day before and even in the hours before you leave. The closer to the time of your hike, the more accurate the forecast will be.

If a thunderstorm is forecast, don’t hike a mountain in that area. 

Allow more time than you think. If storms are forecast early evening but you’re planning to walk in the afternoon, consider skipping it. You might end up out longer than planned and forecasts are not always to-the-minute accurate. 

But what if you DO get caught in a thunderstorm on a mountain?

We all know the weather forecasts aren’t accurate 100% of the time.

So what do you do if indeed you do find yourself in a thunderstorm on a mountain?

Here’s what to do.

1. Get lower

If you are on a summit of an exposed ridge line, get off it as safely as you possibly can. Lightning takes the shortest route to Earth which is why it will strike the tallest object in its immediate area generally speaking. 

So make your way lower as quickly and as safely as possible.

2. Estimate how far away the storm is

The moment you see lightning, you need to start considering how far the storm is from you and the direction it is moving in. Count the number of seconds between seeing the lightning and hearing the thunder. Divide the number of seconds by three and this gives you a rough estimate to the number of KM between you and the storm. For example, if there’s 9 seconds between the lightning flash and the and thunder, you can assume the storm is around 3km away. But be aware that lightning can strike up to 14km from a storm. By calculating this a few times you may be able to get an idea as to whether the storm is getting further or closer.

3. Do NOT shelter under rocks, in caves or under trees

Generally speaking, you don’t get many trees about the 600m elevation level really. So if you’re on a mountain summit, you probably won’t find many trees around. But even if you do, do not shelter beneath them in a thunderstorm. The same goes for rocks and caves as well. If you’re sheltering beneath a rock or overhang, the lighting can essentially “fill” that space between the rock/tree above you and the ground. So you don’t want to be in that space!

4. Avoid wet ground where possible

We’re in the UK. Not always possible, of course. But don’t hanging about in boggy areas or by streams. Water conducts electricity.

5. Make yourself small and round

If you can’t get anywhere less exposed, then sit on your rucksack with your feet up off the ground and curl up as small as possible

6. Move away from any metal equipment

Hiking poles, navigation equipment or anything else you have that’s metal should be kept away from you. If you hear equipment making a buzzing sound, move away from it fast – this could indicate lightning is about to strike it.

7. Nearby bothies 

If you’re close to a bothy, this would be good shelter. Essentially, a solid building with walls and a solid roof or a car if you’re able to get back to the car park (not a soft top) are your best shelter options

8. Give it time

Once you have suitable shelter or have removed yourself from the riskiest places, don’t be tempted to get back to your activity as soon as you think the storm is over. Allow 30 minutes from the last thunder/lightning before you consider it safe

Let’s hope we never need to do this, eh…

Personally, i’m hoping never to be caught out on a mountain in lightning. But it’s useful to be aware of what to do in this and a whole host of other hazardous weather scenarios when you hike mountains as a hobby.

 

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