Returning heat to challenge Northern California firefighters

CALISTOGA, CA - AUGUST 25: Firefighters head to their trucks with supplies at the LNU Lightning Complex Fire incident command center at the Calistoga Fairgrounds in Calistoga, Calif., on Tuesday, Aug. 25, 2020. New safety precautions are being follow

Hot, dry weather returning to parts of Northern California threatened to make conditions worse for firefighters who struggled to contain massive wildfires after a brief cooling trend last week.

Crews working on a fire complex — a group of blazes — in wine country had contained 56% of it by Sunday, up from 42% a day earlier, according to the California Department of Fire and Forestry Protection.

The fires burning in rugged hills north of San Francisco have scorched 586 square miles of brush and trees, destroyed more than 1,200 homes and other structures, and killed five people.

Nearly 2,800 firefighters are battling the blazes ignited by lightning 13 days ago during a record-breaking heat wave.

Firefighters took advantage of cooler temperatures and higher humidity in recent days. But a high pressure system moving through inland regions will wick moisture from the air and bring renewed heat for the next week or so, said National Weather Service meteorologist Brayden Murdock.

“The bit of good news is the system might reduce inland winds. That might be a plus when it comes to fighting fires — less wind,” Murdock said Sunday. “But conditions will be much drier, so that's the trade-off.”

There's unlikely to be a repeat of lightning-packed thunderstorms that sparked so many of the fires, he said.

The weather service issued a fire weather watch for exposed slopes and ridges in interior Del Norte County and the far northeastern end of Humboldt County starting at 5 p.m. Sunday and through 11 a.m. Monday.

"Fuel conditions are near or exceeding critical thresholds over much of our area,” the weather service said in a statement.

Around the state, hundreds of wildfires — coming months earlier in the season than expected — have killed at least seven people, burned more than 2,000 square miles and pushed firefighter resources to the breaking point. Two fire complexes in the Bay Area are among the largest blazes in recent state history.

To the south of San Francisco, about 20,000 residents were allowed to return to neighborhoods in San Mateo and Santa Cruz counties, where a massive blaze caused by lightning was 35% surrounded, fire officials announced.

The fire has burned at least 575 homes. But the tally could rise, and tens of thousands of people remained under evacuation orders.

In the eastern San Francisco Bay Area, a fire that has burned in seven counties was 50% contained. The blaze has charred about 589 square miles of brush and timber, Cal Fire said.