Advice for driving in fog: when to use your fog lights

Advice for driving in fog: when to use your fog lights
Fog lights need to be used at the right times to combat reduced visibility otherwise you could be a danger to yourself and other motorists.

Foggy conditions can be extremely dangerous to motorists, pedestrians and other road users so it is essential to take the correct precautions to reduce any risk.

To help motorists drive to the best of their abilities in these types of weather conditions the RAC has put together a guide of useful information to best advise you on how to drive in fog and when to use your fog lights.

What should you do when driving in fog?

Rule 235 of the Highway Code states that, before entering fog, you should check your mirrors, then slow down. It is also advisable to maitain a greater distance between you and the car in front, you could increase the gap to four seconds from the recommended two. 

If the word ‘fog’ is shown on a signal, but the road is clear, be prepared for a sudden bank of fog or drifting, patchy fog.

Did you know that mist and fog are actually very different things? There is also a phenomenon called freezing fog

When should you use your fog lights?

Fog lights and when to use them

Fog lights should only be used in the fog. The Highway Code states that you must use your headlights when visibility drops below 100 metres (roughly the length of a football pitch): there’s no legal requirement for you to use your fog lights, but not using them when appropriate could impact upon the safety of yourself and those around you when driving. 

Furthermore, if while driving in fog your car is involved in an accident and you weren't using your fog ligts, it could form the basis of an insurance query, which might lead to you being unable to claim.

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Use your common sense. If the fog is so severe that you’re struggling to see other vehicles, switch on your fog lights. But don’t keep switching them off and on again, as this can confuse other drivers. Do not use full beam, because the fog reflects the light back, reducing visibility even further.

Do not attempt to navigate using the tail lights of the car in front, as these can give a false sense of security.

If visibility is very limited, wind down your windows at junctions and crossroads to allow you to listen out for approaching traffic. If you really cannot see, you should consider stopping until it is safe to continue.

How to check your lights and bulbs

It is highly advisable to check your lights before setting off.

During the autumn/winter season when there is more chance of fog it is key to ensure your car is in the best running state to tackle the conditions before it, meaning it is highly advisable to check your  lights are working before setting off.

Make sure you’re familiar with how to operate your front and rear fog lights before setting off, and don’t confuse these with your vehicle’s ‘full beam’ setting.

Automatic lights and daytime running lights

If your car is fitted with automatic lights activated by low light levels, remember to check the lights are on, as they may not be automatically activated in foggy conditions.

READ MORE: What actually is fog and what causes it?

Similarly, drivers whose vehicles have daytime running lights should ensure rear lights are switched on as most vehicles with this feature only illuminate the front lights.

Do all cars have to have fog lights?

All cars must be fitted with rear fog lights as it’s a legal requirement. If your car has been imported, it will need a rear fog light before it is allowed to be used on the road.

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Front fog lights are not a legal requirement, but if your car has them you should only use them when visibility is severely restricted.

Is it against the law to drive with your fog lights on when visibility isn't reduced?

The Road Vehicles Lighting Regulations 1989 prohibits the use of front and rear fog lights to dazzle other drivers when visibility is not reduced or when the vehicle is parked. Using fog lights in drizzle and rain is therefore not allowed.

Once the fog has lifted, switch off your fog lights. There will be symbol on your car’s dashboard or on the fog light button itself: it’s normally an amber indicator for rear fog lights and a green one for front fog lights.

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