People driving home for Christmas are urged to be "very savvy" about their travel plans as Storm Barbara hits the UK.
Millions of people face a "nasty cocktail" of potential road disruption, the AA has warned, on what is expected to be the busiest day for traffic over the festive period.
The Met Office has issued yellow warnings of wind across vast swathes of the UK, including one for the North East of England.
The warnings of gusts - ranging from 60 to 90 miles per hour - are in place until midnight tonight.
An AA spokesman said: "Drivers are going to have to be very, very savvy about how they travel over the next four to six hours," adding: "All in all, it's a pretty nasty cocktail of potential road disruption."
The Met Office said there is potential for some structural damage - more likely across the northwest of the warning area - as well as disruption to power supplies and travel, with restrictions on bridges and disruption to ferries.
Heavy rain teamed with strong winds will bring poor driving conditions, forecasters said.
The AA predicts about 12 million cars will be on the roads due to a combination of people visiting loved ones, shopping trips and holidays, as well as those travelling to and from work.
Scotland is expected to bear the brunt of the storm from lunchtime, but the Met Office has issued several yellow weather warnings, including one for the North East of England.
It lasts from this afternoon through this evening, with gusts of 60mph to 70mph expected quite widely, and forecasters say there is the possibility of structural damage.
Winds are expected to subside tonight, and tomorrow will be calmer, but a further spell of windy weather is expected on Christmas Day, with gusts of around 50-60 mph likely, particularly over high ground.
Some disruption to travel is possible and driving conditions may be difficult for high-sided vehicles.
* If the weather damages their local power network and affects electricity supply, people can call 105, a free new national phone line,
The number is available to people in England, Scotland and Wales, regardless of who they buy electricity from.