How to Deal With Driving In Fog

Driving in heavy fog is like driving with a blindfold on.

Statistically it's the most dangerous driving hazard in existence. No matter how important the trip is, it's not worth gambling your life. By far the safest thing to do if you run into fog is to move well off the road and wait for the fog to lift. However, the simple and safe solution is not always the most practical, so read on to find out what driving procedures should be followed in fog.

driving in fog


What is fog?

Fog and mist are both made of tiny water droplets suspended in air. The difference between them is the density. Fog is denser so contains more water droplets than mist. For pilots, if you cannot see further than 1000 meters, then it is called fog. For most people including motorists though, visibility has to be less than 200 metres before it is classed as fog.

Driving in fog

  • Take particular care when driving in fog, especially at night. Fog can be patchy, going from a light mist to a thick blanket in an instant. Obviously, the faster you drive in these conditions, the less time you will have to avoid danger.
  • As you enter fog, check your mirrors and slow down. Use your foot brake lightly so that your lights warn following drivers.
  • Use dipped headlights and fog lights if visibility is reduced so you can be seen. But remember it's an offence to use high-intensity rear foglights in clear conditions (that is, if visibility is greater than 100 metres). Make sure your main beams aren't turned on by accident. Main beams direct light up into the fog, making it difficult for you to see. Dipped headlights direct light down onto the road and help other drivers to see you.
  • Keep an eye on your speedometer because studies show that some drivers acclimate themselves to foggy conditions and unconsciously increase their speed over time. If you can see less than 12 metres (40 feet) ahead, your speed needs to be reduced to less than 20mph.
  • Use your windscreen wipers and demisters.
  • Beware of other drivers who are not using their headlights.
  • If you park your car on a main road, try and get your vehicle completely off the road. You could be rear-ended!