What should you do when driving in fog?

Driving in fog can be a risky business, we've highlighted some major info that could help you complete your journey safely

Ian Dickson
Sep 16, 2021

Fog is one of the most difficult and dangerous weather conditions to drive in. Over the years, it’s been a factor in some of the country’s highest-profile pile-ups because drivers didn’t adjust their driving to suit the conditions. Fortunately, it doesn’t get foggy very often in most parts of the country, but it’s still vital to know how to drive in fog.

When the fog rolls in, there are a number of steps you can take to ensure you and others around you remain safe on the roads this winter.

It's common sense, but the first thing you can do is check the weather forecast before you travel. Fortunately, most of us have smartphones with weather apps that give up-to-the-minute forecasts. Check the weather at your location and destination because fog can be patchy. If fog is due, ask yourself if you really need to make that journey, if it's not essential you're probably best staying at home. For essential journeys with a risk of fog, it may be worth your while packing some of the same items you’d pack in a winter car kit, such as a coat, torch and phone charger.

What to do when driving in fog?

First things first, if you drive into fog switch on your headlights – even if you have auto headlights; don’t automatically assume they’ve come on. Resist the temptation to put on your full beam headlights, because fog has a very annoying habit of reflecting the light back at you, which reduces your visibility further still. You also run the risk of dazzling a driver coming towards you.

Check your mirrors regularly to maintain a constant awareness of your surroundings and slow down to keep a safe distance from the car in front. Be confident with the speed you’re travelling that you've given yourself as much of a chance as possible of reacting to any hazards up ahead, but at the same time don’t slow down to a crawl, as you'll become a hazard for drivers behind you. Try to maintain a steady pace.

This is especially important on faster roads like motorways. If the word ‘fog’ is displayed on a roadside sign but the road looks clear, be prepared for a patch of fog up ahead.

The rear lights of other cars can give you a false sense of security so don’t follow them. If a driver is following too closely behind, resist the urge to speed up. if necessary, pull over and let them past.

Driving in fog requires all your senses so we’d recommend turning off the music, putting down your window and listening out for other cars near you. Turn on your heater as well because fog can cause condensation on the inside of your windscreen.

Pay particular attention when pulling out of junctions. Listen – as well as look out - for other cars and don’t assume they’re using their headlights. Move off without hesitation and never stop across the road.

When to use fog lights

According to the Highway Code, fog lights must only be used when visibility drops below 100 metres. That’s about the length of a football pitch. If you’re driving on a 30mph street and can’t see the next street light, you should put on your fog lights.

The law doesn’t say you have to put on your fog lights, but if you have an accident and you weren’t using them, your insurer might dispute your claim. You must, however, switch on your car’s headlights when visibility drops below 100 metres.

When the fog clears or if you’re sat in traffic, don’t forget to turn your rear fog lights off again or you could dazzle other drivers and obscure your own brake lights – and land yourself with a fine. Incorrect use of fog lights could earn you a non-endorsable fixed penalty notice and a fine of £50 (but no penalty points).

It’s a legal requirement that all cars have rear fog lamps but many cars these days also have front fog lights that cast a low, wide beam allowing you to see where the edges of the road are. Some models, particularly if they have LED headlights, don’t have separate fog lights but feature a special fog mode that programmes the headlights a certain way. You’ll be able to find out more in your car’s handbook.

It’s worth testing your fog lights if you’re unfamiliar with how they work. In most cars, they can only be used when the headlights are on. When they are on, a coloured fog-light symbol appears on the dash (it looks like a lamp with three horizontal lines crossed by a wavy vertical line). Some cars have different symbols for front and rear fog lights, in which case you can tell the difference by the position of the horizontal lines. If they’re dipped downwards, that’s the light for your front fog lights.

Many cars on the road will have LED daytime running lights but don’t assume that this will be enough to allow other motorists to see you clearly. With just daytime running lights on, you might have plenty of light at the front and your dashboard might be illuminated, but no lights will be on at the back of the car.


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