Up to 10 million cars are expected to clog up Britain’s roads today as the start of the Christmas getaway is marred by train delays and flooding.
Families are travelling around the country as schools break up and shoppers are flocking to high streets and shopping centres to buy presents.
The AA estimated that of the 10 million cars on the road, a third would be driving more than 20 miles.
Edmund King, president of the driving organisation, said: "The Christmas getaway could be a long drawn-out ordeal this year, with a particularly busy start today.
"This is because most schools break up today, Christmas shopping gets going in earnest and consumers have more money in their pocket because of low pump prices."
Wales is set to have the busiest roads with 42 per cent of drivers there saying they will do significant festive mileage today, a survey of 16,165 AA members found.
The North East follows closely behind with 41 per cent and London is likely to suffer least from an early Christmas traffic surge.
The AA added that the most-likely traffic hotspots are near shopping centres close to motorway interchanges, such as Cribbs Causeway off the M5 at Bristol, Lakeside and Bluewater centres off the M25 in Essex, Sheffield's Meadowhall off the M1 and the Metrocentre off the A1 at Gateshead.
Travellers attempting to avoid the traffic by getting the train are also facing problems, with delays on Southern, Thameslink and Gatwick Express services caused by a signal failure at Burgess Hill in West Sussex.
Delays were expected between Brighton and Gatwick Airport until at least 10.30am, according to National Rail.
During the morning rush hour there was also trouble for South West Train' passengers held up by a broken-down train at Wimbledon, while a signalling problem near Canley in the West Midlands led to delays to services run by the CrossCountry, London Midland and Virgin Trains.
In Kent and East Sussex, signalling problems between Ashford International and Rye caused hold-ups and in northern England, safety checks at Crossflatts in North Yorkshire led to delays to trains between Keighley and Shipley.
On the Welsh border, flooding meant trains had to be replaced by buses between Shrewsbury and Machynlleth, with the disruption likely to last until at least noon.
The delays came as British Transport Police warned people to beware the dangers of packed train carriages – a haven for pickpockets.
Property thefts have fallen 14 per cent across the national rail network since April, and 20 per cent on the London Underground, but officers are urging rail passengers not to be complacent as the Christmas rush approaches.
Police are patrolling stations across the country and offering advice to Christmas travellers and commuters.
Additional reporting by PA