Jon Hamm and Anna Osceola Enjoy a Beach Day in Santa Barbara

Jon Hamm and Anna Osceola are soaking up the sun!

The couple was photographed enjoying a beach day on Saturday in Santa Barbara, California.

Hamm, 49, was shirtless for the outing and sported white swim trunks. Osceola, 32, wore an olive green two-piece swimsuit. They were seen walking in the sand before taking a quick dip in the water. They were also spotted lounging in beach chairs and sipping on beverages.

"They had a beach day in Montecito with a picnic. Both seemed to love the warm weather," a source tells PEOPLE. "They looked very happy together. They definitely seem to be dating."

Word of Hamm dating his one-time Mad Men costar first spread in June. They were seen leaving a coffee shop together in 2017, along with a number of outings this year, from picking up dinner to playing tennis together.

RELATED: Is Jon Hamm Dating His Former Mad Men Costar Anna Osceola?

In the May 2015 series finale of Mad Men, ″Person to Person," Osceola played the receptionist at the spiritual retreat where Don Draper (Hamm) ended up.

Hamm sparked dating rumors with producer Lindsay Shookus last September after they were attended a Broadway play together. The speculation was put to rest after a source close to Shookus, who previously dated Ben Affleck, told PEOPLE that she and Hamm ″have been friends for over a decade."

Prior to Osceola, Hamm dated ex Jennifer Westfeldt for 18 years. After splitting in 2015, Hamm opened up to InStyle about the breakup, saying that being single ″after being together for a long time″ was ″really hard."