Nationals outfielder Jayson Werth will undergo surgery on the acromioclavicular joint in his right shoulder on Friday and will require two to three months of rehabilitation, which could put the veteran’s availability for opening day in jeopardy.

Werth originally hurt his right shoulder — diagnosed as AC joint inflammation — in August, missed a week and needed a cortisone shot to relieve the pain. The shoulder joint inflammation affected Werth’s range of motion and forced him to adjust his swing to avoid the pain. Werth still hit .338 with six homers and 19 runs batted in the final six weeks of the regular season.

Werth’s surgery comes late in the offseason. Nationals position players are expected to report to spring training in Viera on Feb. 24, a little more than six weeks after the surgery. After the season ended, General Manager Mike Rizzo said no Nationals players were expected to undergo offseason surgery. Rest was recommended for Werth’s shoulder during the winter. But the shoulder emerged again as an issue recently, as players start to ramp up their offseason workouts.

“I’ve been dealing with this issue since I banged my shoulder on the fence in August, if you remember I received two cortisone shots during the season for this issue,” Werth said in an email to the Post. “There was hope that it would heal with time and treatment, I pretty much did everything legally possible to not have surgery but in the end surgery was the best course of action with the 2015 season and beyond in mind.”

Werth said the “major shoulder tissue” has not been harmed, nor the rotator cuff or labrum, which is a good sign. The AC joint procedure will be done with a scope, which is minimally invasive, and performed by Diane Dahm of the Mayo Clinic in Rochester, Minn.

“I am fully confident in her, her staff and her care during this procedure and expect a full recovery,” Werth said. “I will continue to work and play hard for my city, my teammates and all Nat fans with the hopes of bringing a title home to DC. I would like to thank everyone for there thoughts, prayers, and support as we work diligently through this process. Go Nats.”

News of the surgery was originally reported by FOX Sports.

If Werth’s recovery requires closer to the three-month end of the projected rehab spectrum, he would be ready to return on April 8. The Nationals open their season at home on April 6 and have an off day on April 7. So Werth wouldn’t be in danger of missing a substantial chunk of the season if there are no complications.

Without Werth in the meantime, the Nationals can turn to the other seven outfielders on their roster. Werth, Bryce Harper and Denard Span are the everyday starters. Nate McLouth, the Nationals’ primary backup outfielder, is expected to be ready for spring training after undergoing surgery on his torn right labrum last August.

Other outfield options include veteran utility man Kevin Frandsen (.259 in 105 games last year); speedy infielder-outfielder Jeff Kobernus, who split time between Class AAA Syracuse and the big leagues last year; and Tyler Moore, who is out of options but has experience in left field and at first base.

Perhaps the most intriguing substitute would be 23-year-old Michael Taylor, who climbed from Class AA Harrisburg to Syracuse and up to the Nationals last season. Taylor is the top-rated outfield prospect in the Nationals’ system and the closest to big-league ready after the trade of Steven Souza Jr. in mid-December. Taylor hit .205 in 17 games with Washington last season but shows flashes of his power and speed.

The Nationals could also look outside the organization for outfield insurance. Should McLouth not be fully ready for spring training, the Nationals could consider bringing back Nate Schierholtz, a player they liked last season. The Nationals added the veteran left-handed-hitting outfielder in late August to fill McLouth’s role and he hit .225 in 23 games.

The surgery Werth is expected to undergo is similar to that of teammate Ryan Zimmerman. In October 2012, Zimmerman, who has had more extensive shoulder injury history than Werth, underwent arthroscopic surgery to clean up the AC joint in his right shoulder, but also had a bone spur shaved down and was given a six-week recovery time-frame. Werth’s shoulder is expected to be cleaned up in the surgery.