The first of four Waterville Rocks! concerts will be held Thursday beginning at 5 p.m. in Castonguay Square.

The concert series, which also includes shows on Aug. 11, Aug. 25 and Sept. 22, is hosted by the Waterville Opera House and sponsored by a variety of area businesses. The free outdoor concerts wrap up around 9 p.m.

Thursday’s lineup includes Yard Sail, a 2016 Maine Academy of Modern Music Slam Battle of the Bands runner-up; Sweet & Savory; Chris Ross & The North, a 2014 New England Music Awards Songwriter of the Year winner; Emilia Dahlin; and The Jason Spooner Band. Lineups for the future concerts also feature a variety of different types of music. For details, go to centralmaine.com and search “Waterville rocks.”

If it rains on any of the performance dates — Thursday’s forecast calls for thunderstorms — the events will be held in the Opera House.