Red Flag Warning, Critical Fire Weather, 55 MPH Wind Gusts In The Bay Area

SAN FRANCISCO — Very low humidity and strong offshore winds will create critical fire weather this week, and a red flag warning will be in place for most of the Bay Area between Tuesday and Thursday.

Starting Monday, the National Weather Service said widespread winds were on track to hit 20 to 30 mph, with gusts reaching up to 50 mph in higher elevations. As relative humidity tumbles as low as 15 percent, and improves little at night, forecasters warn dry fire fuels will be "primed" for ignition.

"The combination of the aforementioned winds and humidity will translate to fire exhibiting a large resistance to control, thereby creating a hazardous and extreme wildfire environment," the weather service said. "Fire crews and residents are urged to remain abreast of the weather forecast over the next couple of days."

The red flag warning will take effect at 11 a.m. Tuesday across the interior Bay Area, as well as San Francisco, the Peninsula Coast, and the Bay Shoreline.

Forecasters expect wind gusts will generally be strongest at higher elevations, but could also top 50 mph in parts of Napa and Sonoma counties.

"Offshore winds are anticipated to increase early Tuesday morning and persist through Thursday morning," the weather service said. "North to northeasterly wind gusts will average between 25 and 50 mph, particularly across the higher terrain of the Santa Cruz Mountains, East Bay Hills, North Bay Mountains, as well as interior portions of Napa and Sonoma counties. In particular, these areas of Napa and Sonoma counties have an increased likelihood of wind gusts in excess of 55 mph late Tuesday and through the day on Wednesday."

According to the National Weather Service, the Bay Area will be at a "moderate" risk from weather-related hazards Tuesday before reaching the "major" risk level Wednesday around the North Bay, East Bay, South Bay, and Peninsula.

Forecasters expect fire hazards will start to ease by Thursday afternoon as the low-pressure system exits to the east. Fire conditions should continue to improve heading into the weekend, ahead of a slight chance for some drizzle forecast on Saturday.