Christmas travel tips: Best and worst days to fly or drive

Millions of Americans are gearing up to hit the highway and take to the skies ahead of the holidays.

Here's what you need to know before packing your bags:

Holiday travel by air

AAA predicts this holiday season will be the busiest ever for air travel, with 7.5 million people projected to fly from Saturday, Dec. 23 to Monday, Jan. 1. This would break the record high of 7.3 million flyers set during the 2019 holiday season.

Thursday, Dec. 21 and Friday, Dec. 22 are forecast to be the busiest days for departures, according to Hopper.

Domestic airfares are averaging $349 round trip -- a 3% increase from last year, according to Hopper.

The cheapest days to fly will be Dec. 19, Christmas Eve and Christmas Day, according to Hopper. The most expensive days are Dec. 22 and Dec. 26.

United Airlines said it expects its busiest-ever holiday travel season, with about 9 million passengers planning to fly from Dec. 21 to Jan. 8. This is a 12% jump from last year.

United said it anticipates Dec. 22 and Dec. 23 will be its busiest days for Christmas travel, while Jan. 2 will be the busiest day for New Year's travel.

MORE: Southwest hit by record $140M fine for holiday service meltdown in 2022 that left millions stranded

Delta Air Lines is preparing for nearly 9 million customers during its holiday travel period, which runs from Dec. 21 to Jan. 7.

Delta said its peak days are expected to be Dec. 21 to Dec. 22 and Dec. 26 to Dec. 30.

Holiday travel by road

AAA expects 104 million people to hit the road over the holidays -- a 1.8% increase from last year.

The busiest days are forecast to be Saturday, Dec. 23; Thursday, Dec. 28; and Saturday, Dec. 30, according to transportation analytics company INRIX.

If you're leaving for the holidays on Dec. 23, the best time to head out the door is before 10 a.m., according to INRIX. And if you're heading home the day after Christmas, the roads will be emptiest before noon, INRIX said.