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It's the most wonderful time of the year. That is, unless you have to fly somewhere.

Airfare booking data from online travel agent Travelocity shows domestic airfare this holiday season is 9 percent more expensive than last year. The average cost of a round-trip domestic ticket is $414, inclusive of tax. An international ticket costs $990, 6 percent more than last year.

And prices are only expected to go up in the coming days. Rick Seaney, CEO of Fare Compare, estimates travelers will pay an extra $5 for every day they wait to purchase holiday airfare through the second week in December and $10 per day the following week.

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But not all days are created equal when it comes to finding a cheap (ish) flight home for the holidays. Travelocity conducted a day-by-day analysis of prices over the Christmas travel season to find the cheapest days to fly. Not surprisingly, Dec 24 and 25 come in at some of the least expensive days. But it may be worth it: Travelers who choose to depart December 23, 24 or 25 and return later in the week can save up to $379 on their airfare as opposed to those who leave the weekend before Christmas.

Date combinations to avoid: Dec 21 / Dec 29, Dec 21 / Dec 30, Dec 22 / Dec 30, Dec 22 / Dec 31, Dec 22 / Jan 1. Travelers departing and returning on these dates will pay more than $500 on average for their airfare.

Cheapest date combinations: Dec 25/26: $187; Dec 25/Dec 27: $283; Dec 25/ Dec 28: $329; Dec 24 / Dec 27: $330.

Incorporate any of the following dates into your travel plans to bring down the cost of your ticket: Dec 24, Dec 25, Dec 26.