Depending on the level of fog, driving in the fog can be seriously dangerous. If the level of fog is extreme, you may want to consider if your journey is vital and really necessary. The Highway Code says that if visibility is less than 100 metres, you may use your fog lights.
Although fog is rarely a problem, it is one of the hardest conditions to drive in, so it is essential to know how to drive in fog safely. You should always turn on your basic lights in fog, even if it is light fog and you should switch over to fog lights when visibility becomes less than 100 metres ahead. As soon as visibility becomes better, you must switch off fog lights to avoid dazzling other drivers. Similar to driving in the rain, you need to keep a reasonable distance between you and the car in front. Fog can be misleading, and it can appear as if you are further away from the vehicle in front then you are.
Top tips for driving in the fog
Here are some tips for driving in the fog that should assist in keeping you safe whilst driving in the fog:
- If your car has automatic lights, it will not detect the fog and turn them on/off for you.
- If you have an accident in serious fog levels and your lights aren’t on then this could affect whose fault the accident was. At the same time, if your lights are on unnecessarily, you could be at fault for an accident you believe wasn’t your fault.
- Switch your fog lights off the moment you believe visibility is greater than 100 metres.
- 100 meters looks like the following: length of a football pitch, 100m running race track, tall as Big Ben clocktower, 2 x 50 meter swimming pools, Almost the length of a hockey pitch, 3/4 lengths of a netball court.
- If the visibility is poor in front of you, ensure you have used dipped headlights, wipers and demisters first. If visibility is still less than 100 meters, put your fog lights on.
- Beware of other road users not using headlights/fog lights.
- Your speed should be dictated on what you see. Less visibility, less speed.
- When going above 40mph, you would usually use the 2-second rule. You should increase this to 3 seconds to create a safer gap. This will give you more reaction time to whatever the vehicle in front does while driving in the fog.
- Mirror checks in poor weather are even more important. Remember, mirrors before slowing down, increasing speed, changing direction or any hazards.
- When approaching blind junctions, it may benefit you to wind down the window. Sometimes you can’t see but can often hear approaching vehicles first.
Why shouldn’t you use your fog lights in light fog where visibility is less than 100 metres?
Fog lights are seriously bright. If you’re not careful, your front ones could blind oncoming vehicles. The rear fog lights are red, so when you brake, it is less likely that vehicles behind you will notice your brake lights coming on.
Fog can make driving on country roads increasingly harder as there are no street lamps, so it is crucial to know how to correctly use fog lights. We have many pupils who take driving lessons in Ipswich which is surrounded by country roads, meaning that it is imperative for their driving instructor to go through the suitable situations to use fog lights.
Fog lights definitely have their benefits, but if they are left on by accident or used unnecessarily, it could seriously affect other road users.
Fog light symbols – what do they look like?

This is the front fog light symbol. The indicator is active only when the fog lights are activated. The wavy line crossing straight ones is supposed to depict light passing through the fog.

This is the rear fog light symbol, also only visible when the fog lights are on. The lines point to the right in this symbol, indicating a rear facing beam. They make the vehicle more visible in the fog.
What happens if there is fog on your driving test?
If there is fog on your driving test and visibility is less than 100 metres, there is a very high chance your test will be cancelled and rescheduled by the DVSA. You will not lose your fee, but you won’t be able to take your test that day even if the weather conditions improve. Always call your local test centre 1 hour before your driving test to find out what is happening. Unfortunately, you can’t call earlier as the weather can always change and whoever answers the phone will usually say to call back within 1 hour of your test, unless the weather is serious like 3 feet of snow. With weather conditions such as fog, the examiner may even say turn up to the test centre and they will make a decision just before going out on your test.
If the test gets cancelled because of the weather you will receive a new test date for the same test centre in the post or by email, usually within 10-14 days.
If you are going to test with your driving instructor then you will probably need to commence your pre-test lesson and your instructor will call the test centre while in your lesson.
We asked Jeff Hockley, who provides driving lessons in Bournemouth, about his experience of fog before driving tests and he said the following, “I’ve had many tests go out even though, in my opinion, the level of fog was borderline before the test. I’ve never had a test cancelled at the test centre, though on a few occasions I have called the test centre in advance. They couldn’t give me a straight answer whether the test was going to happen in 50 minutes time. They just said turn up and we will make a decision when you get here and it’s closer to the candidates test time. I even had a situation where I was training someone up to become a driving instructor and the fog was definitely less than 100 meters and the adi part 3 test still went ahead.”