Driving in Fog: A 10-Point Checklist for UK Motorists

Fog is one of the few weather conditions that can turn a familiar road into something unrecognisable. It hides junctions, softens kerbs and makes speed feel slower than it is. The good news is that most fog-related problems are preventable with a few sensible checks and habits. Use this ten-point checklist before and during your journey.

Before You Set Off: A Five-Minute Check

Fog rarely appears alone. It often arrives with damp, cold air, so your car may be misted up before you even start. Begin with a proper walk around.

• Clear every window, mirror and light lens. Fog magnifies glare and smears, so a dirty windscreen becomes a diffused blur.
• Check your dipped headlights, rear lights and fog lights are working. Ask someone to help, or use reflections in a window or garage door.
• Top up screenwash with a winter-grade mix. Grit and spray from wet roads will use it quickly.
• Test wipers and demisters. If the blades leave streaks, replace them.
• Make sure your phone is charged and stored away. You may need it for a diversion or a delay, not for scrolling.

Give yourself extra time. A journey that takes 20 minutes in clear conditions can easily take 35 in fog. Tell someone where you are going and when you expect to arrive, especially on rural routes.

The Right Lights, Used Correctly

Dipped headlights first

Light use is where many drivers get fog wrong. Dipped headlights are your default. They throw light down and ahead without bouncing back at you. Full beam is the opposite: it reflects off water droplets and creates a wall of white.

Fog lights: when and when not

Fog lights are for serious visibility problems, not for ordinary drizzle. The Highway Code says you may use front and rear fog lights when visibility is seriously reduced, generally when you cannot see more than 100 metres. That is roughly the length of a football pitch. When visibility improves, switch them off. A rear fog light left on in clear air can dazzle the driver behind and mask your brake lights.

Quick rule: if you can see the car in front comfortably and the road ahead is clear, you probably do not need fog lights. If you are guessing where the kerb is, use them.

Speed, Space and What You Can Actually See

The speed limit is a maximum for good conditions, not a target for fog. Your safe speed is the one that lets you stop within the distance you can see to be clear. That might be 20 mph on a country lane, or 40 mph on a dual carriageway where fog is patchy. The number matters less than the principle.

Increase the gap to the vehicle in front. In clear weather, a two-second gap is a minimum on dry roads. In fog, think in terms of four seconds, or more. If the car ahead disappears into grey, you are too close.

Avoid sudden braking. Use your brakes gently and early so your brake lights warn those behind. If you are being tailgated, do not speed up to escape. Ease off, increase your own gap, and let the other driver pass when it is safe.

On the Road: A Step-by-Step Approach

1. Settle your speed before you enter the fog. Braking hard in poor visibility unsettles everyone around you.
2. Use dipped headlights and fog lights as needed. Keep them on.
3. Watch the left-hand kerb, lane markings and cats' eyes. They are often more reliable than the tail lights ahead.
4. Open your window slightly at junctions. Listening for traffic can help when you cannot see far.
5. Signal early and check mirrors more often. Other drivers may not see you until you are close.
6. Avoid overtaking unless you can see far enough to complete the manoeuvre safely. In thick fog, that is rarely possible.
7. Be ready for patchy fog. It can clear for 100 metres and then thicken again. Do not speed up just because you can see a little further.

When Fog Gets Worse: Stopping Safely

If visibility falls to the point where you cannot continue safely, find a proper place to stop. A lay-by, service area or car park is ideal. Avoid stopping on the carriageway, in a live lane, or on a bend. On a motorway, use a service area or an emergency area if one is available. If you break down and cannot reach a safe place, move as far left as you can, switch on hazard warning lights, and call for help. If you can leave the vehicle safely, stand behind the barrier, away from the carriageway. If you cannot, keep your seatbelt on and wait for help.

Do not use hazard lights while driving simply because it is foggy. They are for warning others of a hazard, such as a sudden queue or a breakdown. Using them while moving can confuse other drivers and hide your indicators.

What Not to Do in Fog

A few habits make fog far more dangerous than it needs to be.

• Do not follow tail lights too closely. They can lure you into someone else's stopping distance.
• Do not use full beam. It reflects back and reduces what you can see.
• Do not rely on sat-nav alone. It cannot see a fallen branch, a cyclist or a stalled car.
• Do not stop in a lane to check your phone or read a map. Find a safe place first.
• Do not assume the fog is the same everywhere. Valleys, bridges and open fields can be much worse than the road behind you.

A Final Word: Arrive Late, Not Never

Fog rewards patience. The drivers who get through it safely are rarely the fastest; they are the ones who slow down early, leave room, and accept that the journey will take longer. Check your lights and glass before you leave, use dipped headlights and fog lights properly, and keep your speed within the distance you can see. If it gets too thick, pull off the road somewhere safe and wait. A late arrival is always better than a collision.

Photo: garten-gg / Pixabay