The Sheriff's Office says 35-year-old Danielle Staley was last seen at a bonfire on November 6, around 11 p.m., near Rio Del Mar State Beach in Aptos.
Her belongings were found on the beach.
Detectives say new information suggests she may be at risk and foul play may be involved. They say she was last wearing a dark hoodie sweatshirt and leopard-print leggings.
Investigators are asking anyone in the area with surveillance video to review their footage from November 5-7 for possible sightings or clues.
Stay with ABC7 News for updates on this developing story.