More gradual cooling is expected throughout the region on Monday.
The fire started June 27 five miles east of Fort Garland in Costilla County. The cause of the fire is under investigation.
California Gov. Jerry Brown declared a state of emergency, citing "extreme peril" to people and property.
The flames forced more than 2,000 people to flee their homes, and left thousands more without power, prompting the emergency declaration which frees additional funds for the firefighting effort.
As of Sunday morning, the fire has grown to 30,500 acres and is 25 percent contained. Firefighters had begun inspecting the fire zone, which covers an area almost three times the size of San Francisco.
Facilities used to provide water to Yreka and Hornbrook are also in the path of the flames, officials said.
The area was hit by gusty winds that tossed embers and much of Southern California sweltered as temperatures topped 100 degrees in many areas.
Parts of the San Isabel National Forest are closed. He was injured on July 5 in the Klamathon fire burning on the California-Oregon border. Fueled by hot, dry winds, the newspaper wrote, the fire "ignited a tree, jumped the river and spread into nearby hills". Ray Haupt, chairman of the county Board of Supervisors, said losses included homes and livestock.
Elsewhere in California, the 138-square-mile (357-square-kilometer) County Fire northwest of Sacramento was almost 50 percent contained. It had destroyed 18 structures and damaged eight others by Saturday morning. The blaze has burned about 75 square miles (193 square kilometers) and destroyed 90 structures, including homes, cabins, sheds and garages, since starting Sunday in the mountains.
Officials have opened up the burned-out area near a popular fishing lake 80 miles (130 kilometers) southeast of Salt Lake City, as well as a stretch of highway.
In Colorado, firefighters took advantage of occasional rainstorms to extend their containment lines at several large wildfires.
The 400-acre fire was only 5 percent contained, but crews had virtually stopped its growth and were focusing on knocking down hotspots that continue to threatened houses and mobile homes, state fire officials said.
Firefighters are making progress on a wildfire that has burned more than 130 homes and blackened almost 170 square miles (440 square kilometers) in southern Colorado.
Authorities said one person was killed in the fire.
The fire was partially contained, but crews struggled in steep, rugged terrain. The highway had reopened earlier Saturday only to be shut down a short time later due to increased fire activity.