The AA has issued an alert to UK drivers this week as autumn fog returns, advising motorists to increase the gap between vehicles to at least three seconds.
Weather experts at the Met Office have cautioned that mist and fog will become "important features as the week progresses." Night-time fog is anticipated in the coming days as meteorological conditions become calmer and more stable.
Fog drastically reduces visibility, making it considerably more difficult for drivers to properly assess their speed, determine the distance to the vehicle in front, or establish whether another car is in motion or stationary.
The three-second rule
During normal, dry road conditions, the conventional guidance is to maintain a two-second gap behind the car ahead. However, during foggy conditions, the AA advises motorists to increase that gap to at least three seconds.
Drivers are being encouraged to reduce their speed and travel only as fast as enables them to stop comfortably within the distance they can clearly see ahead.
Edmund King OBE, Director of the AA Charitable Trust, warned drivers against falling into common traps in murky weather.
He said: "Fog can transform a familiar road in a matter of minutes, so drivers need to be prepared to adapt their speed and leave more room between themselves and the vehicle ahead.
"One of the biggest mistakes is simply following the rear lights of the car in front. It can give you a false sense of security and means you may be travelling too close to react safely if that vehicle suddenly stops."
Don't rely on automatic headlights
Drivers are also being warned not to place complete trust in modern vehicle technology when visibility deteriorates.
The AA cautions motorists against depending entirely on automatic headlights, as numerous vehicle sensor systems will not activate in foggy daylight conditions. Depending on daytime running lights is similarly hazardous, as they often leave the back of the vehicle entirely unilluminated. Instead, drivers should assume manual control and activate their dipped headlights.
Motorists also need to stay especially alert for road workers and roadside recovery crews, who become considerably more difficult to notice when visibility worsens.
Mr King said: "Don't assume your automatic headlights have switched themselves on either. Take control, use dipped headlights and make sure you can both see and be seen."
When to use fog lights
While fog lights are crucial when visibility is severely compromised, understanding when to deactivate them is equally important.
Keeping fog lights on when conditions improve can dazzle approaching motorists. Bright rear fog lights can also mask your brake lights, making it far more challenging for drivers behind to see when you are slowing down.
Because autumn fog is frequently patchy, motorists should be ready to turn their fog lights on and off as visibility fluctuates during their journey. Mr King explained: "If visibility becomes seriously reduced, use your fog lights, but remember to switch them off again when conditions improve as they can dazzle other road users and obscure brake lights."
Using junctions safely
Junctions pose a specific danger when dense fog obscures approaching vehicles.
Drivers are urged to reduce their speed significantly, take additional time to assess the road carefully, and never emerge until they are entirely certain it is safe to proceed.
At quieter junctions in heavy fog, winding down a window can help motorists listen for the sound of approaching traffic they may not yet be able to spot. Road safety experts emphasise, however, that this is purely an additional safeguard and must never substitute thorough visual checks.
Mr King added: "Ultimately, there's no prize for arriving a few minutes early. Give yourself extra time, slow down and drive to what you can actually see ahead."
