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DRIVING IN THE FOG
Know exactly when and how to use your fog lights.
Fog can reduce visibility to almost nothing in seconds. Our guide covers fog light rules, safe speeds, following distances and what to do if caught in dense fog on a motorway.
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Driving in fog — the risks
Fog is one of the most dangerous weather conditions for drivers. It can reduce visibility to almost zero very quickly, making hazard detection extremely difficult. Many drivers underestimate how seriously fog affects their ability to see — and to be seen. Fog can also make the road surface damp and slippery, further increasing stopping distances.
When to use fog lights
You must use your rear fog lights when visibility is seriously reduced to less than 100 metres — roughly the length of a motorway chevron pattern repeated five times. Front fog lights, where fitted, may also be used when visibility is seriously reduced. Crucially, you must switch fog lights off when visibility improves — leaving them on dazzles other drivers and can obscure your brake lights.
Rear Fog Lights
Use rear fog lights when visibility is less than 100 metres. Switch them off when visibility improves — they dazzle following drivers and hide your brake lights.
Reduce Speed
Slow down significantly in fog. Drive at a speed where you can stop within the distance you can see — this is often much slower than the speed limit.
Increase Following Distance
Increase your following distance in fog. Even a moment's distraction at speed in fog can lead to a serious collision.
Use Dipped Headlights
Use dipped headlights — not sidelights and not full beam. Full beam in fog causes a wall of light reflection that actually reduces your visibility.
Watch for Others
Some drivers do not use their lights in fog. Be ready for vehicles that are hard to see. Pedestrians and cyclists are especially difficult to spot.
Don't Rely on Others
Do not assume it is safe because you can see the tail lights of a vehicle ahead. They may be braking or about to stop. Keep your distance.
Fog on motorways and dual carriageways
Fog on motorways is particularly dangerous because of the speeds involved. Motorway fog warning signs and variable speed limit signs must be obeyed. Keep your distance and do not speed up just because you can see a vehicle ahead — motorway pile-ups often start because drivers close the gap in fog. If you can safely exit the motorway, do so and wait for conditions to improve.
Build all-weather confidence with RED
Our instructors teach you to handle all driving conditions safely — including fog, rain and darkness.
