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
Dec 3, 2019

Fog is one of the most difficult and dangerous weather conditions for motorists 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.

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.

What is fog?

Fog is the accumulation of water vapour into a thick cloud that hangs in the air at a low level. It can greatly reduce visibility and can obscure other cars, buildings and roads. Foggy weather significantly affects your ability to see the road ahead, this is what makes it so dangerous as it reduces the time you have to react to potential hazards.

It's denser than mist, of the kind you see hanging over the landscape on a cold morning.

What to do when driving in fog?

First things first if you run into fog, switch on your headlights – and don’t automatically assume they’ve come on. Resist the temptation to put on your full beam headlights, fog has a very annoying habbit of reflecting the light back at you, which reduces your visibility further still.

Check your mirrors to see if there are other cars around and slow down so that you keep a safe distance to the car in front. Be confident that with the speed you’re travelling at that you've given yourself as much of a chance as possible of reacting to any hazards up ahead. Don’t slow down to a crawl, as you'll become a hazard for drivers behind you, try and 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 bank 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, don’t forget to turn your 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.

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, an orange fog-light symbol appears on the dash (it looks like a lamp with three horizontal lines crossed by a wavy vertical line).

Many cars these days have LED day-time running lights but don’t assume that this will be enough to allow other motorists to see you clearly.

 

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