The US Forest Service said "a heavy smoke inversion" had helped to limit the growth of the fire on Sunday, but also meant that firefighters' aircraft were also "mostly grounded."
Fire crews were working above Fort Jones and west of Yreka "to cut off the fire's progress," the USFS said.
The record-breaking blaze was sparked just days after the year's previous largest fire raged in central California.
The Oak Fire near Yosemite National Park broke out in mid-July and spread rapidly, destroying 41 buildings and forcing thousands to evacuate.
California, which is facing a punishing drought, still has months of fire season ahead of it.
In recent years, California and other parts of the western United States have been ravaged by huge and fast-moving wildfires, driven by a warming climate.