Thick fog disrupts morning travel as yellow weather warnings in effect

Yellow weather warnings for dense fog are in effect across parts of the UK as low visibility threatens to disrupt travel on Monday morning.

The Met Office has issued a yellow warning across much of England and eastern Wales running until 11:00 GMT on Monday. An additional fog warning has been issued for Northern Ireland running until 10:00 GMT.

The larger warning covers an area of England and Wales stretching from Canterbury to Cardiff, Hull to St Asaph and Southampton to York, and includes London, Birmingham and parts of Greater Manchester.

Visibility could fall to less than 50m in places, making driving difficult. Bus, train, ferry and flight services could also face delays or cancellations.

The fog will gradually lift through Monday morning, although some patches could linger into the afternoon.

Commuters are also experiencing a chilly start, with temperatures widely falling into low single figures and ground frost likely in many areas.

Heathrow Airport has advised anyone driving there to allow extra time for their journey because "overnight fog has affected visibility on roads" in the area.

"We advise passengers to check with their airline before leaving home and to drive with care," it said on X, external.

Part of M40 southbound has been shut after crash between junction 1A near Gerrards Cross, Buckinghamshire, and junction one for the M25 link road.

Thick fog already blanketed parts of England and Wales on Saturday night, making an FA cup match between Altrincham and Notts County less of a spectator sport.

It also caused a 30-car pile-up on the M20 in Kent, leaving two people seriously injured, as well as a 19-car collision on the A303 in Hampshire.

With a large area of high pressure across the UK, conditions are ideal for the formation of dense fog.

Temperatures overnight into Monday morning dropped to around 3 to 5C across England and Wales which meant moisture at ground level condensed into water droplets, creating cloud - which is essentially fog.

Light winds then meant fog was able to get denser through the night, leading to visibilities less than 100 meters on Monday morning.

Fog has been particularly dense and widespread on Monday morning because there has also been a lot of fireworks and bonfires over the last few days.

Tiny smoke particules act as extra cloud condensation nuclei which allows more water vapour being able to turn into droplets.

Patchy fog could also develop outside the warning area in northern parts of the UK wherever skies remain clear for long enough.

Mist forms in the same way but is less dense, with visibility generally greater than 1,000 metres (1km).