An expert has settled the debate on exactly when drivers should use their fog lights, offering clear guidance for driving in foggy conditions that have affected much of the UK this week. Heavy fog reduces visibility and makes it harder for motorists to judge distances and react to other vehicles, increasing the risk of accidents.
Expert advice on driving in fog
Mike Thompson, chief operating officer at Leasing Options, said: “83% of drivers believe they are in full control of their vehicle’s stopping distance; only 6% can correctly identify how much extra distance is needed to stop in poor conditions, so being vigilant when the weather is poor is more important than ever. There are clear guidelines for driving in fog, which are outlined in Rules 234 to 236 of the Highway Code and drivers should follow these amid adverse weather conditions.”
Thompson advised drivers to check their mirrors and slow down, as fog can thicken quickly. He recommended keeping a four-second gap instead of the usual two-second gap, because fog can distort depth perception. He also stressed the need to leave enough space to stop safely if other vehicles brake suddenly.
When to use and turn off fog lights
While driving in fog, drivers should use dipped headlights and/or fog lights to maximise visibility. Thompson added: “Remember to turn your fog lights off once you’re out of the fog, as they can dazzle other road users. Failing to do so is a breach of the Highway Code and could result in a £50 fine.”
He also advised drivers to keep checking their mirrors for vehicles without headlights or driving unsafely, and suggested keeping a window slightly open to listen for traffic that might not be visible.
Highway Code rules 234-236
The Highway Code addresses fog in rules 234, 235 and 236. Rule 234 says that before entering fog, drivers should check their mirrors and slow down. If a fog sign is shown but the road is clear, drivers should be prepared for a bank of fog or drifting patchy fog ahead, and can suddenly find themselves in thick fog even if it seems to be clearing.
Rule 235 explains what to do when driving in fog: use lights as required, keep a safe distance behind the vehicle in front, be able to pull up within the distance you can see clearly, use windscreen wipers and demisters, beware of other drivers not using headlights, not accelerate to get away from a vehicle too close behind, check mirrors before slowing down, and stop in the correct position at junctions with limited visibility.
Rule 236 states that drivers must not use front or rear fog lights unless visibility is seriously reduced, as they dazzle other road users and can obscure brake lights. Drivers must switch them off when visibility improves.
