Gloria Daniels was last seen at 10 a.m. near Bailey Road and West Leland Road, according to the sheriff's office.
She is described as a black woman who stands about 5 feet 5 inches tall and weighs about 110 pounds. She has black hair and brown eyes and was wearing a silver jacket and blue jeans when she went missing. She uses a walker and is considered at risk because of her dementia.
Anyone who has seen a woman matching Daniels' description is asked to call the sheriff's office immediately at (925) 646-2441.