Staying Sharp in Foggy Weather

The short rainy season is with us again. Chances are that you will encounter a foggy situation as you drive on our roads. Fog limits what you see ahead of the road. It’s more or less like driving at night with your headlights tuned off. Fog is caused by moisture in the air turning into fine vapour droplets – this happens when the temperature drops to what is called the ‘dewpoint’. You must always use lights if visibility is less than 100 metres. Your lights won’t help you to see in foggy conditions, however, they help others to see you, therefore the more light the better. Use your headlights and fog lamps. Parking or dim-dip lights are as good as useless in daytime fog because they will not penetrate the vapour sufficiently. If the fog is really thick during the day, use full headlights and spot-lamps or stop and wait for the fog to clear.

Using fog lights

Front fog lights are usually mounted low down and give a broad flat beam. This reduces the amount of light that is reflected back by water droplets in the air. The most benefit from front fog lamps can be gained at night, especially on roads with street lighting. Front fog lights will help you see the white lines and kerbs better. Use them with dipped headlights. Full lights are no use because the fog will simply reflect the light back making it harder to see. If the fog is really dense at night, switch off your headlights but leave on your front fog lamps other drivers will still be able to see you, but you will see more clearly because less light will be reflected back by the water vapour in the air. However, if the fog is really dense it’s best not to drive.

Keeping a safe distance

Because you can’t see very far ahead you will have little or no warning if the car ahead of you stops suddenly. This is especially the case if it is using rear fog lights, which can mask the effect of brake-lights. The scenario can be made worse by slippery roads, which often accompany fog. Another problem on high speed roads is that fog can drift, one moment you have reasonable visibility, the next moment, you can see nothing. It doesn’t take a lot of imagination to think what might happen if the traffic ahead stops and you can’t see it. Occasionally you will see people driving fast and overtaking on foggy motorways – these drivers are under a false sense of security on two counts. First, as they drive fast their cars push the air ahead of them giving a false sense of visibility as the fog ‘slipstreams’ over the car. Secondly, the actually believe that the road ahead will be clear. Stay well back and allow yourself plenty of room to stop if necessary.

Other tips

  • Avoid using full beam in fog at night, as the light will reflect back off the fog and reduce what you can see. Apart from dazzling the drivers in front, your full lights can throw a shadow in front of their cars making it harder for them to see.
  • At junctions, wind down your window and listen for other traffic. Sound your horn to warn other drivers that you are there.
  • Check your speed often, especially on normal and highways. You may be increasing your speed without realising.
  • When you stop in traffic or at junctions, keep your foot on the brake pedal until you know that the driver behind has seen you.
  • Use your windscreen wipers and washers often and keep your de-misters switched on.
  • If the fog is really dense, use the left edge of the road as a guide.
  • If you have to park, use a car park or a safe and suitable off-road location.

Ensure that you remain cautious when driving in foggy weather. Check on the vehicles lights before heading out in foggy weather. Visit a KEMRA approved garage, which guarantees you the best repair service for your headlights and other vehicle apparatus. Check our website for the recommended and approved garages close to you.


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