Car AdviceTop 5

Friday Five: Tips on driving in fog

It’s summer time and so tips on driving in fog might seem out of place but where I live fog often rolls in randomly… here’s how to drive to the conditions.

DEPENDING ON where you live in the country will mean you’re more or less likely to copy fog in summer months. So, yep, it’s an odd time to be writing a story like this as fog is more common in winter. But, not where I live… indeed we’ve had foggy mornings twice this week and many people I saw seemed to have no idea what to do. The key thing to remember when driving in fog is that visibility might mean different things to different people.

So, while the law says fog lights can only be used when visibility is down to 100m, a good rule of thumb is, if, when you’re travelling behind someone in fog and thinking it would be nice if they had their fog lights on, then that probably means you should turn yours on.

What is fog?

Fog is basically just a cloud that’s formed out ground level instead of up in the sky. It consists of very small droplets of water that float in the air… indeed, there’s always water in the air, but depending on the temperature alters how much water the air can hold. If the air begins to cool suddenly and is fully saturated with water vapour then the air will lose the ability to hold all of that moisture, causing some of the moisture to condense around tiny particles of dust in the air, forming droplets. If you have enough of these droplets form, then you end up with fog.

Here are five tips to make sure, the next time you’re driving in fog, you’ll get safely to where you want to go.

  1. Switch on your fog lights. A lot of cars now have daytime running lights which generally activate automatically whenever the ignition is on. These are not the same as fog lights. Most cars have at least two fog lights at the front with one rear foglight as standard. Use your foglights the moment you spot the fog or mist as it will make your car more visible – Don’t just rely on your main driving lights, although you should absolutely have these on in fog, or heavy rain (and don’t use your high beams when driving in fog as they will reflect back off the fog making it harder to see or be seen). Unlike daytime running lights, you’re only legally allowed to use your foglights when visibility drops to less than 100m. So, make sure you know where the switch is for your car’s foglights and double-check your insurance policy as some might void your cover if it’s found you didn’t have your foglights on and are involved in a collision.
  2. Watch your speed. Once you’ve turned on your fog lights, depending on the density of the fog and the reduction in visibility, it might be wise to knock 10km/h or more off your speed. The reason is simple, you won’t be able to see as well when driving in fog and so will have less time to react.
  3. Keep your distance. This hangs off the speed monitoring point above. Basically, with the reduced visibility of driving in fog comes a greater risk of collision. You need to be prepared for anything and so giving yourself more room between you and the car in front will give you more time to react. Simple.
  4. Do you have to drive now? Like driving in heavy rain, driving in thick fog can be a little daunting for some drivers. And, so, I’d suggest that if you absolutely don’t have to go out onto the road in fog, then don’t. And the same goes for heavy rain, although in that instance I’d suggest, that if you get caught in a storm when you’re already on the road, you should pull over and wait for it to pass.
  5. Turn off your lights. Well, your foglights. Once the fog has cleared, or you’ve arrived at your destination, then make sure you switch off your foglights. If you don’t, and you’re caught driving with them on by the police, and there’s no fog, then you’ll be fined.

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5 years ago

Good article, but I’d suggest that speed should be dropped by a lot more than 10 km/h. In some of the fogs (or is it cloud?) we get here in Toowoomba, visibility can be down to much less than the stopping distance of the posted limit. That’s a key thing – don’t out-drive your visibility.

Isaac Bober

Isaac Bober