Another round of powerful, dry winds to raise wildfire risk across California

LOS ANGELES — California was bracing Tuesday for another round of powerful winds that will cause humidity levels to drop and raise the risk of wildfires in much of the state.

For the second time in three weeks, a “diablo wind” — notorious in autumn for its hot, dry gusts — was expected to whip up starting in the evening across Northern California.

Forecasters have issued red flag warnings for fire danger until Thursday from the central coast through the San Francisco Bay Area and into counties to the north.

Sustained winds of 25 mph (40 kph) are expected in many areas, with possible gusts topping 55 mph (88.5 kph) along mountaintops, according to the National Weather Service.

During a diablo wind, common in the fall, the air is so dry that relative humidity levels plunge, drying out vegetation and making it ready to burn. The name — “diablo” is Spanish for “devil” — is informally applied to a hot wind that blows near the San Francisco region from the interior toward the coast as high pressure builds over the West.

Pacific Gas & Electric Co. said it was prepared to turn off power to a small number of customers starting late Tuesday in areas where strong gusts could damage electrical equipment and spark blazes.

Targeted power shutoffs were also possible in Southern California, where another notorious weather phenomenon, the Santa Ana winds, were expected to intensify Wednesday and Thursday.

Winds around greater Los Angeles will likely be more powerful than up north, with gusts reaching 80 mph (129 kph), and even higher in mountain locations, the National Weather Service said. A high wind warning was issued starting early Wednesday for much of LA and Ventura counties.