Jillian Mueller as Alex Owens in the production Flashdance at the Kennedy Center. (Jeremy Daniel)

“The Gershwins’ Porgy and Bess” and “Flashdance: The Musical” have something in common. It’s leggings. They both involve a lot of leg warmers. Also off-the-shoulder tops.

I jest, Backstage readers! But both shows will be opening in Washington on Christmas Day, “Porgy and Bess” at the National Theatre and “Flashdance” at the Kennedy Center.

Neither the National nor the Kennedy Center has been home to a Christmas Day opening in at least a decade.

“It’s a matter of practicality,” said “Porgy and Bess” producer Jeffrey Richards. The fact that Christmas falls on a Wednesday throws a bit of a wrench in a planning process that has to cater the logistics of tour travel (“Porgy and Bess” will be coming to Washington from Dallas) and equity rules about the number of performances per time period.

“It’s always a very big week for the theater,” said Richards. “The [Christmas] celebration is usually during the day, and people do go out for entertainment at night.”

“I guess in an ideal circumstance, you wouldn’t be opening on Christmas,” said David Kitto, vice president of marketing at the Kennedy Center. He “had some concerns” when the date was first brought to his attention. “But in terms of sales, we’re expecting to sell out.” “Flashdance” will play in the Eisenhower Theater, which has 1,100 seats. As of Tuesday morning, there were 66 seats available for Dec. 25. “It turned out to be a non-issue.”

“I’m happily surprised by it,” he said.

Kitto expects that some people “probably make a tradition out of doing something Christmas night,” after the in-laws start to get grating and the hours-old Hess trucks are tossed aside. “We’ve always done really solid business on Christmas. ”

The Millennium Stage program also runs on the holiday, said Kitto, and it typically “drives about 1,000 people” to the Kennedy Center on Christmas Day.

The week between Christmas and New Year’s is a much more reliable high-traffic time for theaters, said Kitto. “I think people tend to, as the bills are coming in and have to be paid, change their spending habits a bit after the New Year.”

Kitto said that “a complement of staff” has to work on Christmas to manage the Kennedy Center during a show.

For “Flashdance” cast member Alison Ewing, working on Christmas is nothing new. “I’d say I’m home for 50 percent of Christmases, and this is one of those years that I’m not,” said the Iowa native.

The “Flashdance” cast, all of whom had Thanksgiving week off, will be celebrating amongst themselves — there’s a Secret Santa and everything — and Ewing’s husband will fly out to be with her. They’ll all be spending New Year’s Eve at the Kennedy Center as well.

Ewing has been on the “Flashdance” tour for three months; the tour started just over a year ago and still has six months left in its run. “It’s interesting because the definition of family is kind of changing, and I know that when you’re doing a show with all these different actors, they really do become your extended family,” said Ewing. “So it’s really good to have that sort of support during the holidays, when you can get sort of lonely away from your real family.”

Ewing said that there is a certain infectious spirit in the air during Christmas Day performances. (Insert the “What a Feeling” joke of your choice here.) “Although we’re working, you can feel from the audience that they’re happy, that it’s the holiday, that they’re really glad to be there,” she said. “Everyone is in this extra-wonderful mood.”

Flashdance: The Musical
Dec. 25-Jan. 19, 2700 F St. NW, www.kennedy-center.org,

The Gershwins’ Porgy and Bess
Dec. 25-29, 1321 Pennsylvania Ave. NW, www.thenationaldc.org,