Westerly winds are forecast to pick up over Saturday.
“Dangerous coastal conditions can be expected too, with large waves an additional hazard,” the Met Office added.
Transport Scotland said road, rail, air and ferry services are “all likely to be affected by the conditions” with cancellations and restrictions on bridges possible.
RAC spokesman Rod Dennis said: “With the weekend bringing a mix of strong winds along with heavy, and in some places wintry, showers, it’s going to make many of the estimated seven million getaway trips by car a pretty exhausting experience.”
Speaking to BBC Radio 4’s Today programme, Mr Dennis said he expected traffic to be heaviest on Saturday and Christmas Eve.
On Saturday, roads are expected to be busiest between 11:00 GMT and 16:00 to 18:00, and he urged drivers to “be patient”.
“These are journeys that matter to us this time of year, don’t expect to get there the minute your sat-nav says you will. Allow yourself a bit of time to make it easy and get there safely.”
Nearly 14 million drivers are expected to take to the roads during the weekend – a new record, according to the RAC.
It predicts that congestion hotspots could include:
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Both directions of the M1 to Gatwick via the M25 and the M23
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Liverpool to Chester on the M53
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Oxford to the south coast via the A34 and the M3
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The M25 to the south coast along the M3
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The Taunton to Almondsbury Interchange in Bristol heading down the M5.
The winds are expected to ease by Monday, but it is “absolutely not” looking like a white Christmas, according to Met Office meteorologist Alex Deakin.
Instead, the UK will see “a grey Christmas” which “is going to be very, very mild”, he said, with cloud and rain set to move in.
Away from the roads, the first of the rail closures taking place over the festive period began on Saturday, with a section of the Midland Main line will closed between London St Pancras and Bedford until 29 December as projects costing £29m are completed. This will affect travel to Luton Airport.
Engineering works will also impact other stations over Christmas, including Paddington and Liverpool Street in London, as well as in the Cambridge and Crewe areas.
Asked why so many trains are cancelled over Christmas for work to take place, at a time when people might be more likely to make leisure journeys and use trains if available, Robert Nisbet, the director of nations and regions at the Rail Delivery Group, which represents National Rail and train operators, said “plenty of thought” goes into closures and the festive period is chosen because “on the whole fewer people travel” then.
“The reliability of services is not where we want it to be across the network, we as an industry hold up our hands up to that… but in many cases it is because of the infrastructure,” he told BBC Radio 4’s Today.
Because of this, “essential engineering works and upgrades” are required, he said, adding that these are planned “at a time we feel fewer people are travelling and that is around this period.
He continued that the engineering works would improve services and reliability
Meanwhile, the Port of Dover says it is expecting 25,000 cars to pass through it this weekend.