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Live forecasts update automatically; written guidance last reviewed 20 June 2026 by the Current UK weather desk. Data from national met services via Open-Meteo.
When a moderate fog warning is in force, expect visibility below 100 metres and plan extra time for morning commutes or any road travel. The warning typically covers inland areas and persists until late morning, when sun or wind usually lifts the fog.
What does a moderate fog warning mean?
A moderate fog warning from the Met Office indicates that fog is likely to cause some disruption, particularly on roads, railways and at airports. Visibility can drop suddenly below 100 metres, making driving hazardous. The warning often applies overnight and into the morning, especially in valleys, near rivers and across central and southern England. Motorists should use dipped headlights, reduce speed and allow greater stopping distances.
How should I adjust my travel plans?
If you are travelling in the morning, check local traffic and airport updates before setting off. Allow at least 15–20 minutes extra for short journeys and more for longer motorway trips. Train services may run at reduced speed, while ferries and flights can face delays. Walking or cycling in fog also requires care – wear bright or reflective clothing and avoid poorly lit paths.
Is fog dangerous to drive in?
Yes, because visibility can drop suddenly to less than 100 metres. Braking distances become unpredictable and other drivers may not see you. Use fog lights when visibility is below 100 metres, and do not tailgate. If conditions worsen, pull over safely and wait for it to lift.
How long does a moderate fog warning usually last?
Most fog warnings are in place for 6–12 hours, typically clearing by late morning as the sun warms the ground or a breeze strengthens. In winter, fog may linger all day in some sheltered spots. Check the 10 Day Weather Forecast UK for local clearing times.
Does fog affect flights and trains?
Yes. Airports may reduce landing rates or divert flights, causing delays. Trains often run at slower speeds for safety, especially on lines without modern signalling. Always check with your operator before departing. For the latest conditions, visit the UK weather hub.