Easter traffic is expected to peak on Thursday and Friday with Britons warned to brace themselves for a wet and windy weekend.
The RAC said drivers will complete nearly 19 million separate leisure journeys by car over Easter - the first big getaway weekend of the year.
But those hoping for spring sunshine will be disappointed, as temperatures will be lower than average and heavy rain is forecast.
A study of drivers' plans conducted by the RAC indicates that the largest number of trips will take place on Good Friday with 4.45 million individual journeys being taken, closely followed by Maundy Thursday and Saturday which are each expected to see 3.18 million individual trips.
It is Thursday that is likely to see the largest overall number of vehicles on the road, as cars carrying families and friends vie for space with commuter traffic.
Drivers are being warned to expect unsettled weather, with snow possible on the eastern side of Scotland, mainly over higher ground.
Met Office meteorologist Martin Bowles said low pressure in the south is going to cause "wet and windy" weather, with heavy showers expected.
Temperatures in the south will be "below average but not exceptionally cold", with frost expected overnight, he said.
People in the south will wake up on Easter Sunday to lows of 1C or 2C, with the mercury plunging to as low as minus 2C in the north overnight.
As Sunday progresses, temperatures in the south will climb to around 8C or 9C - lower than the average 11C or 12C.
But Mr Bowles said any talk of a third coming of the Beast from the East is "exaggerated".
Planned upgrades to some parts of the national rail network will likely see an increase in road traffic through the weekend, with buses carrying rail passengers in some parts of the north west, south west and east of England.
Easter traffic hot spots are set to include the M25 between Gatwick Airport and M1, the M3 south west of London, the A303 Stonehenge, the M55 between Preston and Blackpool, and the M53 between Liverpool and Chester, according to the RAC.
Highways England said it is helping people travelling to seaside locations, ports and airports by removing some 300 miles of roadworks.
The organisation said this means around 99% of motorways and major A-roads will be roadworks-free in time for Easter.
Highways England's customer service director, Melanie Clarke, said: "Safety is our top imperative and we know from experience that almost half of breakdowns are avoidable and these can easily be avoided with simple vehicle checks.
"Easter is always a busy period on the road network and we'd urge all motorists to make sure they do their bit to check their vehicle is roadworthy before setting off over this period."
RAC traffic spokesman Rod Dennis said: "The 'Beast from the East' might have departed but much more unsettled conditions look set to make a very unwelcome return - with the risk of snow for some of us, and strong winds and rain for a lot of the country.
"We strongly recommend motorists keep abreast of the weather forecast through this week to help them organise their trips, especially if they are planning on driving any great distance."