“Although good progress continues on the fire, there is much work to be done,” the update said. Officials said several evacuation orders had been changed to fire advisements.
Some areas are not accessible to bulldozers so crews on foot cut in a fire line, and smoke from the fire hampered the response from the 24 helicopter units involved.
There have been no firefighter injuries reported since the blaze began, the cause of which is under investigation.
More than 1,100 structures remain threatened.
On Tuesday morning, Cal Fire officials said in the overnight incident report: “Fire crews continue providing structure defense, extinguishing hot spots, and building and improving direct lines. Persistent drought, critically dry fuels, and tree mortality continue to contribute to the fire’s spread.”
More than 3,000 personnel are tackling the fire, deploying air and land efforts including two dozen helicopters, 286 fire engines, 68 water tenders and 94 bulldozers, according to Cal Fire.
The challenging terrain and abundant dry vegetation fueling the fire has complicated efforts to tamp down its growth, Cal Fire spokesperson Cpt. 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 on 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.
An evacuation shelter has been set up at Mariposa Elementary School for displaced residents.
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.
