28th January 2026
How to drive safely in fog: your complete guide
Fog can appear suddenly and dramatically reduce visibility, making it one of the most dangerous driving conditions you'll face.
So, whether you're caught off guard by unexpected fog or planning a journey when foggy weather is forecast, here's what you need to know:
- When and how to use your fog lights properly.
- Essential techniques for safe driving in poor visibilty.
- What to do if conditions become too dangerous to continue.
Why is driving in fog dangerous?
Visibility can drop to just a few metres in dense fog, making it nearly impossible to spot hazards, other vehicles, or even road markings until you're dangerously close. This creates a false sense of security, with many drivers unconsciously speed up because their peripheral vision is limited, making them feel like they're moving slower than they actually are.
Thick fog also distorts your depth perception, so judging distances becomes extremely difficult. You might think the car in front is much further away than it really is, or misjudge how fast oncoming traffic is approaching.
The combination of reduced visibility and impaired judgement has led to some of the UK's worst motorway accidents – where multiple vehicles collide because drivers simply can't see what's ahead until it's too late.
What should you check before driving in foggy weather?
- Check all your lights are working. This includes headlights, brake lights, and indicators. Clean the lenses too, as dirt can reduce their effectiveness when you need them most.
- Make sure you know how to operate your fog lights before you need them. Locate the switches on your dashboard or steering wheel stalk, and test them whilst parked to ensure they're functioning properly.
- Clear all windows completely, and use your demisters and wipers to remove any condensation or dirt. Fill up your windscreen wash resevoir, as you'll likely need it more in foggy conditions.
- Check your tyres have adequate tread depth and proper pressure, as wet roads from fog increases stopping distances significantly.
Use low beam headlights and fog lights
- Switch on your low beam headlights as soon as visibility drops below 100 metres - roughly the length of a football pitch. Never use full beam in fog, as the light reflects back off moisture particles and creates dangerous glare.
- Fog lights should only be activated when visbility becomes seriously reduced. Look for the symbol showing a wavy line with light beams on your dashboard or steering wheel stalk.
- Turn off fog lights immediately when conditions improve. The Highway Code requires you to switch them off when visibility returns to normal.
Follow road markings and stay in your lane
When visibility drops, road markings become your lifeline. Focus on the white edge lines running along the left side of the carriageway – these ribbed markings are specifically designed to guide drivers through areas prone to fog and poor visibility.
Don't follow the car in front by watching their tail lights, as this can lead you astray if they make an error or suddenly change direction. Instead, keep your eyes on the road markings, particularly the solid white line on your left.
Listen carefully at junctions – crack open your windows slightly to hear approaching traffic when visibility is severely reduced.
When should you use fog lights: Front fog lights vs rear fog lights
- Front fog lights help you see the road ahead – they're positioned lower than headlights and cut through fog without reflecting light back into your eyes. These aren't fitted to every car, but when available, they illuminate white lines and kerbs more effectively than standard headlights.
- Rear fog lights make you visible to people behind you – they're much brighter than normal tail lights and shine in the opposite direction to warn following traffic of your presence. Every car in the UK must have at least one rear fog light by law.
The key difference lies in their purpose: front lights improve what you can see at a greater distance ahead, whilst rear lights ensure others can spot you from behind. Both should only be used when visibility drops below 100 metres, and switched off immediately when conditions improve.
What do fog light symbols look like?
- Front fog light symbols show a lamp pointing left with diagonal lines slanting downward through a vertical zigzag line – this typically appears green on your dashboard when activated.
- Rear fog light symbols point in the opposite direction, displaying a lamp facing right with straight horizontal lines cutting through the same zigzag pattern. These usually illuminate amber or yellow when switched on.
You'll find these symbols on dashboard buttons, steering wheel stalks, or touchscreen displays depending on your car. Some vehicles combine both symbols on a single control, whilst others have separate switches. Check your owner's manual beforehand so you're not fumbling around trying to locate them when visibility suddenly drops.
What lights should you use when driving in fog?
- Dipped headlights are for when visibility starts to drop. Switch these on as soon as you notice the fog thickening, even during daylight hours – they help other drivers spot you from a distance.
- Rear fog lights can be activated when visibility falls below 100 metres. These bright red lights cut through the murk and warn traffic behind you of your presence.
- Front fog lights can also help if your car has them fitted, but they're not essential for safe driving.
Never use full beam headlights in fog
Why? Because the light bounces back off water droplets and creates a dangerous wall of glare that actually makes visibility worse. Stick to dipped beams combined with fog lights when conditions are particularly thick, and remember to switch off your fog lights once the weather clears to avoid dazzling other drivers.
Is it illegal to drive with fog lights on in the UK?
Using fog lights when they're not needed is illegal under UK law. The Road Vehicle Lighting Regulations 1989 specifically prohibit driving with fog lights activated when visibility isn't seriously reduced.
You can face a £30 to £50 fine if police catch you misusing fog lights, though no penalty points are added to your licence. The Highway Code Rule 236 states you must not use front or rear fog lights unless visibility drops below 100 metres – they dazzle other road users and can mask your brake lights.
What to do if visibility becomes too poor
How to safely pull over in fog:
- When fog becomes too thick to drive safely, finding the right place to stop can be life-saving. Look for designated lay-bys, service stations, or car parks rather than stopping on the roadside where other drivers might not see you in time.
- Signal early and check your mirrors before you begin to slow down, giving traffic behind extra warning of your intentions. Pull as far off the carriageway as possible.
- Once stopped, keep your dipped headlights on and activate hazard warning lights immediately. If you're on a motorway hard shoulder, exit from the passenger side away from traffic and wait behind the safety barrier if possible.
Using hazard lights when stopped
- Hazard warning lights become vital once you've pulled over safely in foggy conditions. These flashing amber lights alert other drivers that your vehicle is stationary and potentially creating an obstruction.
- Switch on your hazard lights immediately after coming to a stop – they're far more visible than regular lights in thick fog. You'll find the hazard button marked with a red triangle symbol, usually positioned centrally on your dashboard.
- Keep your hazard lights on for the entire time you're stopped, whether you're waiting for conditions to improve or for breakdown assistance to arrive.
- Remember to turn off all other lights except your hazards once stationary, as brake lights can confuse following drivers into thinking you're still moving.
- Exit your vehicle carefully if it's safe to do so, always using the door furthest from traffic.
You might also want to explore car insurance options that provide comprehensive protection for weather-related incidents. At Allianz, our policies cover you for the unexpected, so you can drive with confidence even when conditions aren't perfect.
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