Bay Area temperatures to cool down, but fire danger is turned up

Temperatures that scorched part of the Bay Area on Tuesday and Wednesday were set to fall by at least double-digits on Thursday, in large part because of winds created by low pressure high in the atmosphere that kept a two-day heat-up from gaining any traction.

Yet, the fire danger figures to be as significant as it has been at any time this year, according to the National Weather Service and fire officials.

“That upper-level low across the Pacific Northwest is causing a pressure gradient across the region,” NWS meteorologist Dial Hoang said Thursday. “That’s causing the winds to pick up in their intensity, especially across the coastal region and some of the passes.”

Those winds are expected to blow steadily with gusts of between 25-40 mph, according to Hoang. He added that there is still on-shore flow but that elements associated with off-shore winds coming from the north also are present

As a result, the weather service issued what it called a “near-critical fire weather threat” into Saturday as humidity is expected to drop to between 15-25 percent. The threat is most dangerous in the East Bay Hills, the eastern Santa Clara Hills and the Gabilan Range of San Benito and Monterey counties, according to the weather service. Hoang said the Altamont Pass also is in the danger zone.

Before that weather settled in, fire crews were forced to tackle a wildfire in Antioch that grew to 290 acres. Crews stopped the forward progress Wednesday night, and had the fire 80% contained by early Thursday, according to fire officials.

PG&E responded to the weather threat by announcing a public safety power shutoff. At 7:30 a.m. Thursday, 489 customers in Contra Costa County were without power, most of them near the area of Kirker Pass Road, though only 91 were the result of the shutdown, according to the utility. In Santa Clara County, about 805 customers were without power.

“Because the winds are so strong, the interior areas are going to get really dry,” Hoang said. “That’s where the elevated fire weather is coming from.”

The gusty winds are expected to continue at least into Saturday and probably through it, Hoang said. Their intensity is expected to drop significantly by Sunday, along with some of the immediate fire danger.

As for the temperatures, they will peak no higher than the low 80s in the hottest places on Thursday, according to the weather service. Most inland places won’t escape the 70s, while coastal temperatures are expected to remain in the 60s. Hoang said they will stay there until at least the middle part of next week.