Scores of flights have been cancelled at Heathrow, Gatwick and Stansted airports and the Tube and train services severely disrupted as freezing fog and heavy snow blanket London - with the wintry weather set to cause chaos for Monday rush-hour travellers.
A yellow warning of snow and ice from the Met Office remains in place until 11am on Tuesday, after a fog warning for the capital on Sunday.
Just after 7am there were delays and suspensions across the entire London underground network, and reports of motorists being stranded on the M25 for three hours. The M25 was closed in both directions at J23 to J25 at South Mimms to Waltham Cross for hours on Monday because of heavy snowfall. It reopened about 8.30am.
National Rail said there would be disruption to Thameslink, Gatwick Express and Southern services until midday. Southeastern warned its customers not to travel on Monday morning. The C2C was running a normal service.