Driving in Fog

Safe driving in fog and reduced visibility

You must use headlights when visibility is seriously reduced

According to the Highway Code, you must use headlights when visibility is seriously reduced – generally when you cannot see for more than 100 metres (328 feet) or the length of a football pitch.

There's no obligation to use fog lights, but they must be switched off when visibility improves. However, if your car is involved in an accident in reduced visibility and its fog lights weren't on, then it may be queried by an insurer.

Heavy traffic is challenging enough, but you should be extra vigilant when driving in fog, as visibility can seriously deteriorate in a matter of seconds.

Use common sense when it comes to fog lights. Some drivers are worried about dazzling other motorists, and some simply don't know how to turn them on.

Generally speaking, it's better to be safe than sorry, so use them when appropriate. Don't keep switching them on and off, though – this can be a distraction, so wait for a consistent improvement in visibility before switching them off.

AA Advice

  • Use dipped headlights at all times and windscreen wipers and demisters.
  • Familiarise yourself with your front and rear fog lights – know how to switch them on and off – and use them when appropriate.
  • Beware of other drivers not using headlights.
  • Only drive as fast as conditions allow and maintain a greater distance between you and the car in front (follow a three-second rule) – tailing someone's rear lights can give a false sense of security and is dangerous.
  • If the road has street lights on, then you probably don't need fog lights on.
  • Be able to stop within the distance you can see clearly – this is particularly important on motorways and dual carriageways, as vehicles are travelling faster.
  • Do not accelerate to get away from a vehicle that is too close behind you.
  • Check your mirrors before you slow down.
  • At a junction with limited visibility, stop, wind down the window, and listen for traffic. When you are sure it is safe to emerge, do so positively and do not hesitate in a position that puts you directly in the path of approaching vehicles.

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12 November 2009