Fog lights and when to use them

Fog Lights – when to use them and when not to!

There’s a lot of confusion of the use of fog lights. If you get it wrong you could be risking your life and the life of others. And you could be breaking the law!

Key points

You must use dipped headlights lights if visibility is reduced. While dipped headlights won’t help you to see in foggy conditions they help others to see you!

And if you don’t have your headlights on foggy weather, you’re breaking the law as well as risking your life.

And it’s dipped headlights – not sidelights or main beam lights. Parking or sidelights are useless and main beam headlights make it harder to see as well as dazzling other drivers.

Rear fog lights

Lots of drivers put on their rear fog lights as soon as it starts to rain or when it gets a little misty. But they’re called FOG lights for a reason…

High intensity rear fog lamps are designed for thick fog, when visibility is 100 metres (the length of a football pitch) or less. Using rear fog lights when visibility is greater than this (or in the rain or a slow moving queue of traffic) can mask your brake lights and dazzle other drivers, thus increasing the risk of a rear-end collision rather than reducing it. Constant, dazzling bright lights can also add to fatigue at night.

Rear fog lights don’t have to be used in foggy conditions but if you do use them (and you should!) they MUST be turned off when visibility improves. But but prepared to turn them on and off as necessary – fog is often patchy.

Front fog lights

Front fog lights will help you see white lines and kerbs better in foggy conditions but make sure you use them with dipped headlights – not full beam lights that reflect the light back making it harder to see.

Don’t use front fog lights when visibility is good. If you do, you could dazzle other drivers.

The UK Highway Code says:

  • Rule 226: You MUST use headlights when visibility is seriously reduced, generally when you cannot see for more than 100 metres (328 feet). You may also use front or rear fog lights but you MUST switch them off when visibility improves.
  • Rule 236: You MUST NOT use front or rear fog lights unless visibility is seriously reduced as they dazzle other road users and can obscure your brake lights. You MUST switch them off when visibility improves.

Note: when the word ‘MUST’ is used in The Highway Code it denotes a legal requirement.

It’s helpful to think of rear fog lamps as signals. Switch on your rear fog lamps when there is no one close behind – but switch them off as soon as they have done their job and the driver behind can see your regular tail lamps. For example, if you are in a slow moving queue of traffic in fog, the driver five metres behind doesn’t need your fog lights!

More tips for driving in fog

  • make sure all your lights are working and your windscreen is clean inside and out;
  • use your demisters or air conditioning to keep your windows clear;
  • use your lights as required (see above);
  • keep a safe distance behind the vehicle in front. Getting too close to the driver in front gives you a false sense of security;
  • be able to pull up well within the distance you can see clearly and especially careful on motorways and dual carriageways;
  • beware of other drivers not using headlights;
  • do not accelerate to get away from a vehicle which is too close behind you;
  • at a junction with limited visibility, stop, wind your windows down and listen for traffic. When you are sure it is safe to emerge, do so positively and do not hesitate in a position that puts you directly in the path of approaching vehicles.

With thanks to Smart Driving and the DVSA