Thick fog is forecast to cover much of the southern half of England, the eastern half of Wales, and most of Northern Ireland throughout the early part of the week. Forecasters have advised commuters to anticipate delays.
Yellow weather warnings, the least severe, have been issued for Monday across areas including most of England south of Manchester (excluding Devon and Cornwall), eastern parts of Wales (including Cardiff), and most of Northern Ireland (excluding Belfast). Visibility may drop to 50 metres or less in some locations.
Disruption to flights was reported at Heathrow Airport on Monday due to overnight fog. A spokesperson for Heathrow advised travellers to allow extra time for their journey to the airport and to check with their airline before leaving home.
The affected area is expected to reduce on Tuesday, covering the Midlands, Staffordshire, Cheshire, Yorkshire, Lincolnshire, and East Anglia.