A fire scorching parts of Northern California’s Butte County — the same county that in 2018 endured the deadliest wildfire in state history — has ballooned into the state’s largest wildfire this year.

The Dixie Fire, which ignited July 13, has burned through 192,849 acres in swaths of Butte and Plumas counties as of Sunday evening, CAL Fire incident commander Nick Truax said in a news briefing. Officials expect more extreme fire behavior ahead.

More than 5,400 firefighters are battling the blaze, which has destroyed 16 structures, including some residences, and is threatening more than 10,000 others as it rages in the two counties.

“The threats and risks associated to this fire are very real,” Mike Minton, an incident commander working on firefighting efforts, said Saturday during a briefing. “We’re observing fire behavior conditions and fuel conditions that are not common for this area. So the rapid rates of fire growth that we’re seeing are very real.”

The fire, which officials said remained active overnight, was 21 percent contained as of Sunday afternoon. Fire officials said late Saturday that the Dixie Fire and the smaller Fly Fire had “come together tonight.” The Fly Fire was most recently reported to be spread across 4,300 acres.

Gov. Gavin Newsom (D) declared a state of emergency on Friday in four northern counties because of multiple fires, including the Dixie and Fly fires.

More than 16,000 people are under evacuation orders in Plumas and Butte counties as of Sunday evening, according to the California Department of Forestry and Fire Protection. Evacuation orders and warnings have also been extended to Tehama County.

“People have lost homes,” Chris Carlton, forest supervisor at Plumas National Forest, said at a news briefing. “These are real-life impacts. Let’s recognize this and support each other.”

The combination of the area’s steep terrain and extreme weather has proved to be one of the major challenges officials face in controlling the flames. Forecasts indicate that conditions will worsen, said Rick Carhart, a spokesman for CAL Fire-Butte County Fire Department.

“What happens is that the fire starts to produce its own weather,” he said. “So there’s a possibility of thunderstorms that could produce some cloud-to-ground lightning, which is always a concern since that lightning could start another fire, and there won’t be really any rain along with that thunderstorm.”

Although the smoke generated by the flames helped limit the amount of heating throughout Sunday’s fire-quenching operations, the upcoming week’s changing winds could hinder efforts, incident meteorologist Julia Ruthford said.

Such winds could dissipate the smoke and enable critical conditions that are expected to progress throughout the week. The elevated chance of thunderstorms coupled with rising temperatures remain major concerns, she said.

Exceptionally dry conditions and high temperatures this year have fueled the growth of wildfires in Western states. Eighty-eight large fires are actively burning in the United States, including nine in California.

The Bootleg Fire in southern Oregon is the largest of the blazes burning in the nation. Some progress has been made in recent days in halting that fire, which had burned more than 408,000 acres as of Sunday and is 46 percent contained.

During a Saturday briefing on the Dixie Fire, officials repeatedly urged residents to heed evacuation orders.

The evacuation orders for the Dixie Fire include communities along the western shore of Lake Almanor, a resort area in Northern California about a two-hour drive north of Paradise — the town in Butte County that was ravaged by the Camp Fire in 2018. That fire, which killed at least 85 people and was the state’s deadliest and most destructive on record, sent people fleeing, with some of them settling in Lake Almanor.

Plumas County Sheriff Todd Johns spoke directly to residents of one community in Taylorsville, Calif., on Saturday, some of whom he said had not yet evacuated.

“You know how steep the mountains are behind you. If you have not done so, I highly encourage you to evacuate if you live on Arlington Road in Taylorsville,” he said. “The fire activity at this point … it’s extreme. Sometimes it’s unpredictable or most of the time it’s unpredictable, and I just ask the folks that live in Taylorsville that are wanting to stay there to reconsider that.”

An investigation of the cause of the Dixie Fire is ongoing. In a preliminary report last week, Pacific Gas and Electric, California’s largest utility, noted that some of its equipment may have played a role in sparking the fire.

In the report filed to the California Public Utilities Commission, PG&E said a utility employee observed on the morning of July 13 a possible blown fuse uphill from where he was located. Because of “challenging terrain and road work,” the worker could not reach the fuse until nearly 10 hours later, when he observed multiple fuses blown as well as a fire near the base of a tree.

In a statement Sunday to The Washington Post, PG&E said it is cooperating with authorities investigating the Dixie Fire.

“The company submitted [an incident] report in an abundance of caution given CAL Fire’s collection of PG&E facilities in connection with its investigation,” a spokesperson said.

To determine the fire’s origin, CAL Fire collected some of the company’s equipment — including jumpers, conductors, insulators and fuse cutouts — as well as portions of the tree where the employee first noted the fire, according to the preliminary report.

PG&E equipment has been linked to numerous California blazes in recent years, including the Camp Fire.

With the Dixie Fire’s flames being spurred by worsening conditions, officials think it will “probably find itself on the list of the largest fires in the history of the state,” Carhart said, if it continues to grow at its current rate.

“Unfortunately,” he added, “like the majority of that list of largest fires in the state, these are fires that have happened in the last decade or so.”

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