High Winds, Dry Conditions Raise Bay Area Fire Danger and Force PG&E Shut-Offs

Updated 1:51 p.m.

Power shut-offs are planned around the Bay Area for the second day in a row Friday as windy, dry conditions that spurred a series of brush fires earlier this week persist across the region.

According to climate scientists, these shut-offs could become more common as Northern California grows hotter and drier on average.

PG&E said that it would keep power off Friday in parts of Alameda, Contra Costa and Santa Clara counties where there’s a high potential for wind-related damage and lower moisture content in the vegetation, both of which increase the risk of a fast-spreading blaze.

More than 100 of the utility’s customers have been without power in inland parts of the counties since Thursday, when winds topped 40 mph at higher elevation. Most of the zones are expected to remain dark until Saturday afternoon, after gusty conditions peak midday Friday.

“Winds have increased significantly today in portions of the East Bay, Sacramento Valley and Salinas Valley, combined with lowering relative humidity, leading to elevated fire danger concerns,” PG&E said in a statement Thursday.

The estimated two-day outages are affecting swaths of eastern and southern Livermore in the East Bay, areas surrounding Highway 152 in Santa Clara County, and Contra Costa County’s Los Vaqueros Reservoir and Black Diamond Mines Regional Park, near where a fast-moving brush fire threatened homes earlier this week.

The National Weather Service’s Bay Area office noted “elevated to near-critical fire weather concerns” for Friday and Saturday in the interior East Bay, eastern Santa Clara Hills, and the Gabilan Range in San Benito and Monterey counties.

UCLA climate scientist Daniel Swain said in a post on his “Weather West” blog that these inland areas — especially at elevations up to 4,000 feet — are drier than usual for mid-June, and are covered with acres of brittle, dehydrated grass that can easily spark, putting them at an increased risk of wind-driven fires this week.

In Contra Costa County, the Somersville Fire adjacent to the outage area ignited Wednesday night and spread more than 350 acres.

Contra Costa County Battalion Chief Bob Atlas said the fire threatened about 150 homes before it was contained Thursday afternoon.

“What we’re battling is the significant winds,” he said. “As the season goes a little deeper, we’re definitely concerned about the humidity going down and the temperatures rising. That’s when it gets really dangerous.”

Smaller vegetation fires in Alameda and Santa Clara counties broke out Monday and Tuesday.

Mark Schwartz, a conservation scientist and professor of environmental science and policy at UC Davis, said that while the Bay Area’s peak fire season doesn’t come until late August and September, fire-prone conditions can begin as soon as May.

This spring was drier and hotter than the average, according to PG&E, and Schwartz said that climate modeling shows this could be a trend in the coming years, when periods of both dry and hot conditions are expected to extend. That could mean more fire risk — and preventive outages.

“What we’ve observed over the last few decades and what we should be expecting in the future is for rains to shut down earlier in the spring and start later in the fall on average,” he said. “That means we have a higher overlap of dry, warm weather with those high wind events.”

KQED’s Maria Fernanda Bernal contributed to this report.