It’s shaping up to be a busy — and expensive — holiday travel season, and some days over Thanksgiving, Christmas, and New Year’s are going to be pricier than others.

Travelers hoping to save should avoid flying on the Tuesday or Wednesday before Thanksgiving and on the Sunday and Monday before Christmas, Going.com shared with Travel + Leisure. In fact, the Sunday after Thanksgiving tends to be the busiest travel day of the year. 

Instead, travelers should consider flying on the actual holidays (Christmas Eve or Christmas Day, for example), which could save them up to 25 percent off the overall ticket cost, according to Going.

“Overall, flight prices coming out of summer are the lowest we've seen in years,” Scott Keyes, the founder and chief flight expert at Going, said in a statement shared with T+L. “This holiday season, Going members can save anywhere from 40 percent to 90 percent on flights, provided they have the right tools. It’s important to understand cheap flights as a matter of probabilities. Each day presents a certain likelihood that a great deal may arise.”

When it comes to New Year’s, returning on Dec. 31 will save travelers money, compared to flying on Jan. 1 — and airports will be less crowded as well.

The advice comes as travelers are expected to spend more on holiday travel this year and as crunch time to book flights quickly approaches. In fact, those who plan to fly over either Thanksgiving or Christmas should book no later than Oct. 14.

Keyes recommended travelers book at least 21 days in advance, and said they shouldn’t wait. Instead, he said to book the next “reasonable” fare they find and monitor prices to see if it goes down, taking advantage of many airlines’ no-change fee policies if it does. 

And for those who don’t mind spending Thanksgiving abroad, Keyes said it’s actually a great time to save on an international trip due to a major increase in domestic travel for Turkey Day.