Twenty-five single residence structures have been destroyed in the fire, the update said — four more than were reported destroyed Monday night. The agency revised downward the number of outbuildings destroyed, from 34 to 16 as of Tuesday morning.
More than 1,400 structures are still threatened.
“Fire crews continue providing structure defense, extinguishing hot spots, and building and improving direct lines,” Cal Fire’s update Tuesday morning said. “Persistent drought, critically dry fuels, and tree mortality continue to contribute to the fire’s spread.”
But challenging terrain and abundant dry vegetation fueling the fire has complicated efforts to tamp down its growth, Cal Fire spokesperson Captain Keith Wade told CNN Monday.
“The footprint out here, the acreage of available fuels to burn when the fire gets going, along with the available topography — the canyons, the drainages — the wind that flows through these areas, can make the fire behavior erratic and it can explode … the ferociousness of that fire at times can be intense,” Wade said.
There have been 23 wildfires in California so far this month, according to Cal Fire, but only three have exceeded 500 acres. None have come close to the mass destruction of the Oak Fire, due in part to the exceedingly dry conditions in the area, Wade said.
“I think the real difference that firefighters are experiencing on this one is how dry everything is, it’s definitely been (drier) as the years have been going on,” he said. “We’ve noticed that there seems to be less precipitation, less moisture and the available fuel load is definitely out there.”
The fire’s rapid growth has also made evacuation efforts more difficult, Cal Fire Battalion Chief Jon Heggie told CNN Monday, noting officials and law enforcement are doing their best to notify residents when they need to leave.
“The reality is, it’s moving so quickly, it’s not giving people a lot of time and they are sometimes just going to have to evacuate with the shirts on their back,” Heggie said.
The incremental progress made by fire crews has allowed officials to reduce evacuation orders in some areas to fire advisements, Cal Fire said.
Heggie attributed the Oak Fire’s “velocity and intensity” to the state’s prolonged drought and human-caused climate change.
“What I can tell you is this is a direct result of what is climate change,” he said. “You can’t have a 10-year drought in California and expect things to be the same. And we are now paying the price for that 10-year drought and that climate change.”
“That dead fuel that’s a result from that climate change and that drought is what’s driving these, what we are now calling, ‘mega fires,'” Heggie said.
The report suggested it’s time we “learn to live with fire,” urging authorities and policymakers to cooperate with local communities to use Indigenous knowledge and invest in planning and prevention efforts.
CNN’s Poppy Harlow, Taylor Romine, Stella Chan, Sara Smart and Rachel Ramirez contributed to this report.