Graduation ceremonies at Sonoma State University are expected to turn nearby roads into parking lots this weekend, with commencement exercises scheduled throughout the day Saturday and Sunday drawing about 12,000 people, police said.

Drivers who don’t need to use the following streets should avoid them through much of the weekend: East Cotati Avenue, Petaluma Hill Road and Rohnert Park Expressway to Highway 101.

Various schools within the university are hosting ceremonies at 8 a.m., 1 p.m. and 5 p.m. each day, resulting in corresponding traffic delays beginning around 10:30 a.m., 3:30 p.m. and 7:30 p.m., the Rohnert Park Public Safety Department said.

You can reach Staff Writer Mary Callahan at 707-521-5249 or On Twitter @MaryCallahanB.