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Why the Park Fire exploded so quickly

The speed at which the Park Fire consumed an enormous area has stunned even those who live and breathe wildfire, and who have watched other historic blazes rip through the region.

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A column of smoke from the Park Fire rises over Highway 32 near Forest Ranch, Calif., on Saturday. (Nic Coury/AP)

Wildfire experts knew the Northern California region where the Park Fire sparked was ready to burn, but no one expected how fast it would go up in flames. In just three days, the fire exploded into the state’s seventh-largest wildfire on record.

It consumed about 5,000 acres per hour after first igniting Wednesday, scorching 150,000 acres on Friday alone and racing far to the north to threaten towns that earlier seemed well out of reach. As of Sunday morning, it had spread to more than 350,000 acres, with evacuation orders spanning four counties.

“This region is no stranger to fast-moving and high-intensity fires,” Neil Lareau, an atmospheric scientist at the University of Nevada at Reno, said in an email. “This fire is right up there with the fastest growing fires in history.”

Multiple wildfire experts and historians — including Zeke Lunder, a veteran wildfire and fuels management expert who lives in Chico, Calif., near where the Park Fire started — said they don’t recall another wildfire that reached 350,000 acres in 72 hours. In 2020, the Bear Fire, part of the North Complex Fire, which burned the town of Berry Creek, came close, he said. The Santa Ana wind-fueled Cedar Fire in 2003 torched 280,000 acres around the San Diego area in the time period.

While each fire is unique, climate and fire scientists have a general sense of when one will be bad and why. The Park Fire, however, has been exhibiting extreme behavior and “moving in ways we aren’t yet used to seeing,” Lunder said.

A volatile mix of ingredients combined to make this particular blaze one of the most extreme the state has seen. Here’s why it has grown so big, so quickly.

Record heat even before ignition

Heat waves have been plaguing California since early May, after the last real rainstorm moved through the state. But the heat this month has been off the charts.

Much of California is on track to see its warmest July on record. That includes Red Bluff, a city just west of where the fire is burning, which also just recorded its all-time hottest 21-day stretch, from July 3 to July 23, according to the National Weather Service in Sacramento.

“Record setting antecedent heat in early July throughout the West set the stage for the explosion of fires we’re seeing now,” Lareau said.

The heat rapidly dried grasses, brush and trees, causing the fire danger to skyrocket.

“What climate change is doing is just adding more energy into the system and amping up what’s there,” said Stephen Pyne, an emeritus professor and fire historian at Arizona State University.

Butte County, where the Park Fire ignited, sits at the epicenter of the state’s wildfire crisis amid increasingly hot fire seasons as global temperatures rise. Many of California’s most shocking recent blazes have roared through this area: 2018’s deadly Camp Fire, 2020’s North Complex Fire that wiped out a town and killed 15, and 2021’s million-acre Dixie Fire.

But this fire is “near the top of the list in terms of the extraordinary, record-breaking, paradigm-shifting fire characteristics that we saw,” UCLA climate scientist Daniel Swain said in a Friday briefing.

The Park Fire, which has quickly spread since igniting on July 24, consumed over 164,000 acres in Northern California. (Video: The Washington Post)

Winds that fanned the flames

After sparking in Chico’s lush Bidwell Park on a triple-digit afternoon last week, the fire exploded around Butte County and, with the help of strong winds, rapidly moved north through all that fuel. Given the highly flammable conditions, any winds were going to be a problem.

“Winds haven’t been extreme … but they’ve been ‘just right’ to produce high-intensity spread,” Lareau said.

At a news conference Saturday morning, Cal Fire officials discussed the extreme conditions they were witnessing, explaining that this blaze is a “plume-dominated fire.” That means the power of the fire is stronger than the wind, and it produces its own convection columns filled with gases, smoke, ash and other fire particles.

Firefighters were dealing with multiple large, fortified plumes, and when those columns rise, “you get a strong inflow of wind,” officials said. When those combine, they can create erratic, gusty winds, which can throw embers far ahead, creating new spot fires that can also take off.

“Independently, a plume-dominated fire is very dangerous. With this one, we have multiple plumes working together,” Scott Weese, a fire behavior analyst with Cal Fire, said Saturday.

In briefings throughout the week, fire officials described how these conditions drove the fire’s fast spread.

“It’s been growing 5,000 acres an hour since the inception,” said Billy See, incident commander for Cal Fire. “Just to put that into perspective, we’re looking at almost 8 square miles an hour this thing is taking out.”

Fuel for the fire

The fire is burning so hot in part because there is so much dry vegetation to consume, with a high fuel load and abundant grasses in the region. And much of where the fire is burning has never burned in modern history, experts said, meaning the fire is ripping through very dense fuels that have accumulated.

“There’s areas out there that have no fire history, a lot of ‘dead and down’ and a lot of logging slash,” Weese said.

Pyne wasn’t surprised to see a blaze like this in this area, given all of the grass growth from two wet winters and then a serious heat dome to dry it all out. California has gone from the lush green of the wet season to severe wildfires in a few short months.

“The cadence [of the fire season] is there, it’s just being compressed and exaggerated,” Pyne said. “So, things shift, but further than they would have in the past.”