Laura Negrete Cerda left her San Rafael home to visit friends in San Jose, police spokeswoman Margo Rohrbacher said. She does not drive and planned to take public transportation.
She told her husband she would return the next day but did not and she failed to appear at work or contact her employer, Rohrbacher said.
Cerda's family waited several days then contacted police, Rohrbacher said. She is not considered at risk but attempts to track her whereabouts have been unsuccessful, Rohrbacher said.
Cerda is 5 feet 1 inch, 240 pounds and has long dyed red hair and brown eyes, police said.
Anyone with information regarding her whereabouts is asked to call San Rafael police at (415) 485-3000 or Crime Stoppers at (800)-222-8477 or online at www.bayareacrimestoppers.com.