Strong winds and low humidity will bring critical wildfire danger to much of the West

Red flag fire warnings are in effect for large portions of the West on Sunday and Monday, the National Weather Service said.

Strong winds and low relative humidity will cause a high risk that any fires that develop will spread rapidly.

Parts of the Sacramento Valley are under red flag warnings from 2 p.m. Sunday through 8 p.m. Monday. Southeastern California, as well as most of the neighboring states of Nevada and Arizona, are also posted. Strong west-to-southwest winds are expected to peak on the Sierra slopes Sunday afternoon and evening, and to weaken but remain near critical levels in northwest Arizona on Monday.

Although the most recent U.S. Drought Monitor showed little change this week in much of the West, fuels are dry, and drought conditions remain widespread.

U.S. Drought Monitor data released Thursday.

(Paul Duginski / Los Angeles Times)

Drought is acute in parts of Northern California, the Great Basin and the Four Corners region.

Gusty winds and low humidity were forecast for the Great Basin and the Four Corners region in advance of a cold front. The cold front is associated with an unusually strong upper-level low-pressure system dropping southward over the western U.S.

Widespread wind advisories in the eastern Sierra and Owens Valley may need to be upgraded on Sunday to high-wind warnings, the National Weather Service said. Wind gusts could exceed 60 mph in those areas.

As the trough moves into the Great Basin, the San Francisco Bay Area is expecting to see winds pick up on Sunday. Gradients will swing around to offshore and strengthen, with dry, gusty conditions overnight in the North Bay hills and mountains, including parts of Napa and Sonoma counties.

A strong Delta breeze with gusts to 45 mph was expected through the Carquinez Strait on Saturday night before northerly winds develop Sunday and Monday, leading to the elevated fire concerns in the Sacramento Valley.

In southwestern California, strong southwesterly winds are expected in the interior sections Sunday, especially in the mountains and the Antelope Valley.