Be prepared for a lot of ugly holiday sweaters if you’re flying Alaska Airlines on Dec. 15.

The carrier will celebrate what it's calling “National Ugly Holiday Sweater Day” by offering early boarding to customers wearing “festive holiday sweaters.” Alaska says the one-day promotion will be offered across its 115-city network, including flights operated by Virgin America and Horizon Air.

"Travel during the holidays can be stressful for guests, especially those who do not travel often,” Natalie Bowman, Alaska’s managing director of marketing and advertising, says in a statement. “This fun promotion not only allows guests to board early on that day, but gives people another opportunity to dust off that ugly holiday sweater hanging in the back of their closet.”

For those unaware, National Ugly Christmas Sweater Day is a thing, “celebrated” on the third Friday of each month.

Alaska Airlines says it will post its customers’ ugly sweater combos to its Facebook, Twitterand Instagram accounts.

Early boarding or not, Alaska Airlines also is reminding customers that they still should arrive early to the airport “given anticipated congestion at the airport due to the holidays.”

However, Alaska Airlines isn’t the only big carrier getting in on the ugly sweater craze.

In November, Dutch airline KLM unveiled its own KLM-inspired Christmas sweaters.

Unfortunately for holiday sweater enthusiasts, KLM’s “Christmas jumpers” appear to have been so popular that the carrier is now out of stock in all sizes.