The Met Office forecast for London and South East England says Wednesday will begin chilly and bright after a clear night, with a few patches of mist and fog possible around dawn. Patchy cloud should develop later and the day is expected to stay dry. For the morning journey, the main challenge may therefore be a short-lived but sudden loss of visibility rather than rain.
Mist can be thin outside your home and much denser a few minutes later near low ground, open fields, rivers or shaded roads. A five-minute visibility check before departure helps you respond calmly if the view changes.
Clear every viewing surface before moving
Remove condensation from the whole windscreen, side windows and mirrors, not only a small patch in front of the driver. Use the demister and air conditioning where fitted, and wait until the glass is genuinely clear. Wipe the inside surface if a film is scattering light, then check that wipers and screenwash work without smearing.
The Highway Code vehicle-maintenance guidance says windscreens and windows must be clean and free from obstructions to vision. It also calls for lights, demisters, wipers and washers to be kept in working order. Clean the headlamps, rear lamps, reflectors, cameras and number plates while the car is safely parked.
Expect fog to arrive in patches
Rule 234 advises drivers to check mirrors and slow down before entering fog. A clear stretch does not guarantee the next section will be clear: roadside signs may warn of a fog bank or drifting patches ahead. Reduce speed before the view closes, rather than braking sharply after visibility has already fallen.
Do not follow the rear lights of the vehicle ahead as if they mark a safe path. They can create a false sense of security and may be much closer than they appear. Keep enough space to stop well within the distance you can see to be clear, especially on faster roads.
Use the correct lights and switch them off again
Use dipped headlights when visibility is seriously reduced. The Highway Code describes this generally as being unable to see for more than 100 metres. Front or rear fog lights may be used in those conditions, but they must be switched off when visibility improves because they can dazzle other road users and obscure brake lights.
Automatic lighting is not a substitute for checking. Daytime running lights may not illuminate the rear of the car, and a bright patch of sky can confuse an automatic system. Confirm the actual light setting before moving and again if conditions change.
Drive to what you can see
Keep steering, acceleration and braking smooth. Check mirrors before slowing, use the brakes progressively so following traffic receives a clear warning, and avoid an overtake if you cannot see enough clear road to complete it safely. At junctions with limited visibility, stop in the correct position, listen as well as look, and emerge only when it is safe.
Give cyclists, motorcyclists, pedestrians and horse riders extra time and space. Pale mist can reduce contrast even when you can still see the road surface, so scan twice before turning and do not assume another road user has seen you.
Prepare for a delay without cluttering the cabin
Carry a charged phone, breakdown-provider details, warm layer, water and a small torch. Secure loose equipment so it cannot reach the pedals or become a hazard during sudden braking. A reflective vest should be accessible before you leave the vehicle, not buried beneath luggage.
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This compact kit combines a high-visibility vest, warning triangle and emergency window-breaker/seatbelt-cutter tool. Store it securely, learn what is included before you need it and use roadside warning equipment only where it is safe and lawful to do so.
Run a final 30-second departure check
Ask four questions: is every window clear, are the correct lights on, can you stop within the visible distance, and is emergency equipment secured and reachable? Reassess after each clear patch because fog can return suddenly. If the view becomes too poor to continue safely, slow down and stop only in a suitable place away from moving traffic.
Sources: Met Office: London and South East England forecast; The Highway Code: adverse weather and fog; The Highway Code: lighting and stopping distance; The Highway Code: vehicle maintenance.
