Freezing temperatures are forecast for Wednesday night into Thursday morning in the North Bay valleys, southern Salinas Valley and southern Monterey County, officials with the National Weather Service said.
On the San Francisco Peninsula and coast and in the South Bay and East Bay, temperatures are expected to drop to 35 to 45 degrees.
The cold weather is due to light offshore winds and few clouds overnight, weather officials said.
Localized areas west of Santa Rosa and in the Alexander Valley will get as cold as the low 20s. The same is true for localized areas in southern Monterey County.
Weather officials have issued a freeze warning for the interior North Bay valleys, the southern Salinas Valley/Arroyo Seco, interior Monterey County, Lake San Antonio, the Santa Lucia Mountains and the Los Padres National Forest and mountains.
Patchy frost may settle in low-lying coastal areas.
Freezing temperatures and frost is expected to kill crops and sensitive vegetation and may damage outdoor plumbing that isn’t protected.
The cold weather will be particularly hard on the 5,000 people still displaced by the Kincade Fire in the North Bay and on those in the more than 200,000 homes without power.
Through the weekend, overnight lows will warm gradually, but remain near or below freezing.