We start this guide with a safety message. It is really important that fog lights are used only at the right times in order to avoid you becoming a danger to yourself and other drivers when visibility is reduced.
To help you stay as safe as possible we wanted to make sure you know how to drive in fog and what it is fog lights actually do to help. As using fog lights at the wrong time could lead to you driving illegally.
How do fog lights help?
A normal car light in fog just scatters the light particles so most of the light makes its way back to you before hitting the road. Fog lights on the front of your car are usually found at bumper level and are cut off at the top so the light is projected under the fog which usually hovers at around 12-18 inches off the ground. Fog lights on the rear of your vehicle are essentially there to make sure other drivers can see your car whilst driving through fog.
What should you do when driving in fog:
- Before setting off, if it is foggy or forecasted to be foggy, make sure you know where your fog lights are and that they are working
- Make sure to check your mirrors and slow down before entering fog
- Always maintain a greater distance between you and the car in front, for instance, you could drive 4 seconds behind the car rather than the recommended 2
- Use your wipers and keep your windscreen demisted to aid visibility (here's our guide to speedy demisting)
- If signs say 'fog', but the road is currently clear, be ready to enter fog, or for the fog to be drifting and patchy
- If you can't see the length of a football pitch, which is roughly 100 metres, use your lights
- Do not use your full beam as the fog reflects the light back, reducing visibility further
- By following the tail lights in front you can give yourself a false sense of security, so this isn't recommended
- If visibility is really limited, wind down your windows at any junctions and crossroads to allow you to listen out for approaching traffic
- If you really cannot see anything you should consider stopping somewhere it is safe until the weather has cleared and it is safe to continue
When your fog lights should be used:
It might seem obvious but fog lights should only be used in fog, when visibility drops below 100 metres, which is roughly the length of a football pitch. Not using your fog lights when it is appropriate to do so impacts on the safety of not only yourself but others around you and it is illegal to dazzle people.
You could also invalidate your insurance if you have an accident in fog and you weren't using your fog lights. But make sure you don't keep turning them on and off if the visibility is bad, keep them on until you can see over that full 100 metres again.
Is it against the law to drive with fog lights on?
If visibility is not reduced or when your vehicle is parked, using your fog lights is against the law. The Road Vehicles Lighting Regulations 1989 prohibits the use of front or rear fog lights to dazzle other drivers. Look out for the light on your dashboard to tell you when your fog lights are either on or off.
All cars are fitted with rear fog lights as a legal requirement in Europe, front fog lights are not as common and if your car does have them only use them when visibility is really severe.