If there’s one day to avoid when booking your holiday plans this year, it’s this: December 19, the most expensive day to travel over the holidays.

Experts at Travelocity.com have identified the cheapest — and most expensive — travel days for the remainder of the year. Not surprisingly, the cheapest days to fly are Christmas Eve and Christmas Day.

The most expensive day will be the Friday before Christmas, December 19, when airfare averages $150 USD more than air travel on December 24.

“If travelers can be flexible with their plans, even by a day or two on either end of the holidays, they can stand to save 10, 20 or even up to 40% compared with the busiest travel days,” said senior Travelocity editor Courtney Scott.

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“For example, departing early on Christmas Day could save enough money to pay for your holiday shopping, yet you will still get to your destination in plenty of time to celebrate with friends and family.”

Meanwhile, though the general rule of thumb for air travel is to book flights as early as possible, experts note that a window of cheaper airfares usually opens about two weeks before Christmas Day.

This year, travelers who already know what they’ll be doing for the holidays are advised to book by November 12, after which time fares are expected to rise.

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And adventurous travelers who are more flexible over the holiday period may want to consider taking a risk and booking a trip about a week before Christmas, when international fares are known to drop.

Though choices may be limited, travelers could find a bargain basement deal for a trip halfway around the world.