The women, Sara Marko, 20 and Brittany Beus, 22, walked away from the minimum-security Blaine Street Women's Facility, and were last seen near Felker Street, along the San Lorenzo River levee, police said.
Santa Cruz County sheriff's Deputy April Skalland said the women are not believed to be armed.
"These aren't high-security inmates," Skalland said.
She said the facility is for inmates who demonstrate that they can be trusted. The women, who were recently brought over from the county's main jail, may have escaped while doing yard work.
"I wouldn't say it happens all the time, but it's not uncommon," Skalland said.
Both were wearing jail clothing, but have likely changed their clothes since, Skalland said. Police today are searching areas the women are known to frequent.
Anyone who spots the women should call 911 immediately. Residents are advised to be especially cautious and report any unusual people or activities.