Services affected so far include:
London Transport
Buses: all but a few have been cancelled. A limited bus service has resumed on a small number of bus routes including routes 16, 36, and 73 in central London
National Express coaches subject to delays and cancellations: worst affected routes are to and from London and the south-east
Bakerloo: suspended Queens Park to Harrow and Wealdstone
Central: services operating
Circle line: suspended
District: suspended Earl's Court to Edgware Road
Hammersmith and City: suspended
Jubilee: suspended between Stanmore and London Bridge
Metropolitan: suspended north of Harrow-on-the-Hill
Northern: services operating
Piccadilly: services operating
Victoria: services operating
Rail
Journeycheck gives updates on all train and underground services.All Southeastern trains into and out of London cancelled. Limited services: Tonbridge to Hastings, Ashford to Maidstone East, Ramsgate to Faversham, Ramsgate to Tonbridge, Faversham to Dover Priory
Stansted Express is suspended
Southern, which operates the Brighton line into Victoria, has reduced its service on all routes to just one or two trains an hour.
South West Trains, which operates local and long-distance routes into London Waterloo, suffered a much reduced service. A spokeswoman said: "We advise passengers not to travel unless their journey is absolutely necessary."
First Capital Connect trains into London from Peterborough, King's Lynn, Cambridge and Stevenage are disrupted.
C2C Services on all routes to and from London Fenchurch Street are subject to alterations and delays of up to 30 minutes
Warning of delays on other lines across England
Airports
Heathrow airport: both runways shut. All flights cancelled until 5pm.
London City airport is closed
Gatwick and Stansted airports are open, although fewer aircraft are able to take off
Some 23 flights had to be cancelled and 18 diverted to other airports after Gatwick closed its runway for two hours on Sunday evening. There is no service on the Gatwick Express
Leeds Bradford International airport, runway reopened, major delays
Roads
AA Roadwatch reports that there are too many incidents to log, and offers users a breakdown of conditions in the area where they live or are travelling to.
A66 in the north-west of England closed between Brough and Stainmore summit
Lanes blocked by snow on the M25
Section of the southbound A1M near Stevenage, Hertfordshire closed between junctions 7 and 6 due to jack-knifed truck
Section of the A66 was also closed on the Cumbria/Durham border
The longest queue of traffic stretched 32 miles on the M25 motorway between Watford and Reigate
London mayor Boris Johnson has suspended the congestion charge for motorists for the day
Schools
More than 50 schools closed in Kent
A total of 54 schools were closed across North Yorkshire and 30 closures in the East Riding area. In West Yorkshire closures in Leeds, Bradford and Kirklees.
400 schools in Essex closed. Three schools in Gloucestershire were closed due to the weather, two in the Cotswolds and one in Cheltenham
50 schools in Birmingham, the Black Country and Wales closed
The website Snowday provides updates for school closures
The Old Bailey and all other London crown courts closed