Motorists are being warned that the West Country faces some of the worst traffic chaos in the country as the great Easter getaway starts tonight.
Two of the major routes are among the top ten hotspots as motoring organisations warn drivers to expect the roads to be even busier than the usual Easter bank holiday rush.
A perfect storm of late school holidays, good weather and engineering works is predicted to create traffic misery from tonight when millions head off to make the most of the good weather before it breaks on Sunday.
And the jams are expected continue into manic Monday when families make their way back home for the start of the school term next week.
But it's not all bad news because the ten million Britons planning short breaks and day trips will give the tourist industry a vital £800 million shot in the arm.
According to VisitEngland at least 3.4 million people are set to take an Easter break in the UK involving at least one overnight stay and a further 6.5 million are planning day trips.
VisitEngland chief executive James Berresford said: "The industry has rallied following the severe weather earlier this year.
"It's business as usual for tourism with a full line-up of events and offers across the country, and destinations ready and waiting to welcome visitors this Easter break."
The RAC said that as many as 18.6 million motorists could take to the roads over the holiday and predict tomorrow, Good Friday, will be the busiest day.
But it warns that with the new school term starting next week, families will be heading home en-masse on Monday rather than staggering the end of their holidays as usual.
Major railway engineering projects on the East and West Coast Mainlines and the Great Western Mainline will also add to the number of vehicles on the roads.
INRIX, the traffic information provider, warns that journeys between London and the West Country on the M4 and trips on the A303 in Wiltshire are likely to take twice as long as usual during busy times.
Both routes are on a list of the top ten routes predicted to suffer the most.
With 1.6 million Britons jetting out of the country this weekend, routes to the London and regional airports are also expected be particularly busy.
Ferry ports will also be busy and Eurostar is expecting to carry more than 130,000 passengers over the holiday weekend – a 15 per cent increase on numbers at Easter 2013.
Although the prolonged period of good weather has led to warnings that Easter could be busier than usual on the roads, forecasters have warned that it will not last.
Today's uninterrupted sunshine and temperatures of up to 17C will give way to clouds and the Met Office say that Easter Sunday and Monday could be a washout.
Tom Tobler, a forecaster with MeteoGroup, said: "On Friday it will be generally fine, though it will be feeling cooler than it has been, and Saturday will be a similar story, so the start of the Easter weekend is looking pretty good.
"However the picture changes on Sunday, when an easterly wind is expected to bring some potentially heavy rain across much of the country. There will be some rain around on Easter Monday as well, but Sunday is expected to be the worse of the two days."
Rail industry body the Rail Delivery Group (RDG) is estimating that around eight million journeys will be made by rail this Easter and said the vast majority of passengers will not be disrupted by the engineering work which will hit many major London terminals.
"Work is planned carefully to deliver faster, more reliable journeys while ensuring that the vast majority of passengers will not be disrupted as we improve the railway," said a spokesman.
Popular foreign spots for those going overseas include Spain and its islands, Turkey, Tunisia and Florida, according to UK travel organisation Abta. Top city destinations are Paris, Dublin, Amsterdam, Rome and New York.
Meanwhile VisitBritain has announced that Welsh singer Katherine Jenkins will lead a renewed drive to attract international visitors to Britain.
She will be at the heart of VisitBritain's Countryside is GREAT advertising campaign which will be launched in September.
Before that, Jenkins will be collaborating in a range of projects showcasing the best of the UK's culture and heritage, including a festival in Istanbul in May and appearances in the US later in the year.
M4 between Hants. & West Country
M25 between J7 and J21A 40 minutes
A456 between M5 and Kidderminster
M4 between London and Reading
M25 J5 Sevenoaks from J3 to J7
M1 between J1 and Luton Airport
M6 between J8 and J10A