Utility Pacific Gas & Electric Co. has begun to shut off power for some Northern Californians on Monday as strong and dry winds are expected to increase the fire risk in the region.
PG&E initially said 44,000 customers in 32 counties would be impacted by planned shut-offs but reduced the scope to 25,000 people in 20 counties on Sunday. The first wave of shutoffs was planned for Monday morning at 4 a.m.
PG&E could not be reached for comment, but a map on the company website showed shutoffs in Contra Costa, Solano, Napa, Yolo, Lake, San Joaquin, Stanislaus and Merced counties.
The shutoffs are due to a dry, gusty wind event that began Sunday night and is expected to bring winds up to 50 miles per hour to some regions.
Portions of 20 counties — including the Bay Area’s Alameda, Contra Costa, Napa, Solano and Sonoma counties — could lose power, the utility said in a news release. Customers can check on the status of their address with this map.
The National Weather Service issued a red flag warning Sunday, saying that gusty, northerly winds could increase fire danger across the Bay Area. The warning began Sunday at 11 p.m. and runs through 5 p.m. Tuesday in the East Bay hills and valleys and the North Bay mountains. The warning began 2 a.m. on Monday for the Santa Cruz Mountains, Monterey County mountains, interior San Benito and the Santa Lucia range.
NWS Bay Area meteorologist Gerry Diaz said a low-pressure system from the Pacific Northwest, called an “insider slider,” will bring dry and strong winds to the Bay Area and mix with high mountains and hills, eventually drifting southward to the Bay shoreline.
“When we have these setups, the concern revolves around when we have 15 to 25% humidity values and very strong winds, all it takes is one spark,” he said. “It’s like a hair dryer that is being directed right at the Bay Area and the hot air is slowly mixing down to the surface.”
Diaz said winds up to 30 miles per hour, with gusts up to 30 to 40 miles per hour during the evening hours, can be expected in areas with elevations below 1,500 feet. For high-elevation areas, including St. Helena, winds could reach up to 50 miles per hour.
Northern areas are seeing gusts up to 40 miles per hour, with East Bay Hills and San Bruno experiences winds around 40 miles per hour, Diaz said.
Humidity is around 50% along coast lines but for elevations above 1,500 feet, including the Santa Cruz mountains, humidity is currently 15-25%, according to Diaz. North Bay Mountains, Sonoma Mountains and Napa mountains in the East Bay are also seeing humidity between 25-35%.
San Francisco is seeing over 50% humidity and portions of the East Bay, including the East Bay Hills, Oakland and Berkeley are trending in the 40-50% humidity range.