It may be May, but Colbie Caillat has December on her mind.  That's because the Grammy-winning singer is currently working on her first Christmas album.

Colbie tweeted, "Writing Christmas songs on a gorgeous Cali day in May," and included a photo of herself sitting on a lush green hillside with her co-writers, ex-American Idol judge Kara DioGuardi and longtime collaborator Jason Reeves.

Colbie has previously released two holiday songs: a version of "Have Yourself a Merry Little Christmas," which appeared on the charity album A Very Special Christmas 7, and "25 Days of Christmas," which she recorded to promote the ABC Family channel's annual Christmas programming.

Colbie will hit the road on a joint tour with Gavin DeGraw starting May 26 in Biloxi, Mississippi.