Friday is expected to be the busiest day during the period from December 18 to January 2, travel trade organisation Abta said.
France, Italy and Austria are the most popular destinations for holidaymakers wanting to enjoy snow.
Many winter sun lovers are heading to the Canary Islands, Turkey, Egypt, Mexico and the Dominican Republic, while popular New Year’s Eve breaks include New York, Amsterdam, Dublin and Barcelona.
Airports will be exceptionally busy, with Heathrow expecting 1.7 million departing passengers over the festive period.
More than one million will jet off from Gatwick, 525,000 from Stansted, 480,000 from Manchester and 330,000 from Luton.
Hundreds of thousands of passengers are also leaving from Scottish airports, with 226,000 passing through Edinburgh alone.
A significant number are also travelling across the English Channel by ferry or through the Channel Tunnel.
Abta chief executive Mark Tanzer said: “Christmas and new year are always a very busy time for the travel industry with people heading off for winter sun or guaranteed snow for a truly authentic Christmas experience.
“For many people the festive period is a really busy time of year, going away for Christmas or new year gives families and friends time to relax, safe in the knowledge that someone else is doing the hard work for them.
“The weather in the UK looks set to be mild over the holiday period, which should help avoid travel disruption, but the roads will be exceptionally busy so customers should allow extra time to get to their departure port and check for line closures and engineering work if using public transport.”