SAN FRANCISCO (CBS SF) – National Weather Service officials Sunday extended a Red Flag Warning through Tuesday evening for the North Bay mountains because the risk of wildfires will be extremely high.

A Red Flag Warning is issued when critical fire weather conditions are occurring or will occur shortly.

READ MORE: Oakland To Spend $5.8 Million To Fill Vacant Police Officer Positions

The Red Flag Warning for the North Bay mountains was extended until 5 p.m. Tuesday.

Weather officials said a Red Flag Warning for the East Bay hills remains in effect until 11 p.m. today.

In the North Bay, the warning was prompted by a forecast for gusty offshore winds and low humidity.

READ MORE: Strome Scores as Rangers Beat Sharks 1-0

Weather officials said gusty winds will reduce the area’s moisture and low humidity at night and in the early morning hours will do a poor job of replacing it.

The greatest threats will be to elevations above 1,000 feet.

Weather officials said any fire that starts will likely spread quickly.  Outdoor burning is discouraged. Downed power lines in remote areas will likely cause a fire to start, weather officials said.

MORE NEWS: Omicron Variant Outbreak Reported In Alameda County Among People Already Vaccinated; Cases 'Mildly Symptomatic'

© Copyright 2017 by CBS San Francisco and Bay City News Service. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.