Firefighters light backfires as they try to contain the Thomas wildfire which continues to burn in Ojai, California on December 9, 2017.

Although a cold front and calmer winds have helped aid firefighters, the massive Thomas fire in Southern California now ranks as the state's largest-ever wildfire, Cal Fire said late Friday.

The flames have charred at least 273,400 acres, or more than 427 square miles. That's slightly above the previous wildfire record of 273,246 acres from the 2003 Cedar blaze in San Diego.

"The Thomas Fire is now the largest wildfire in recorded California history," Cal Fire spokesman Brandon Vaccaro told CNBC late Friday. "The weather has been extremely cooperative, except for some winds we had earlier this week that were not bad."

As of Friday evening, the Thomas fire was 65 percent contained.

If the weather continues to cooperate, firefighters may be able to mop up the remaining portions of the wildfire shortly after Christmas, Vaccaro said. That would end the most destructive and deadly wildfire season in California history.

Just over 2,800 fire personnel were fighting the blaze as of Friday evening, down from about 4,400 crew on Thursday and well below the more than 8,000 firefighters on the lines last week.

There have been at least two fatalities related to the Thomas blaze, including a Cal Fire engineer killed last week on the fire lines.

Thousands of residents in Santa Barbara and Ventura counties were forced to evacuate due to the fire, although officials lifted the orders over the weekend in many areas.

More than 1,000 homes and other buildings were destroyed. The fire didn't discriminate, burning mobile homes and middle-class neighborhoods in Ventura County and multimillion-dollar estates in the upscale Montecito area of Santa Barbara County.

Also, Ventura County agriculture officials say the fire consumed farms with avocados and report there also was a significant impact on local livestock operators, as grazing land was scorched. Some local beekeeping businesses, who supply bees to farms for pollination, also suffered extensive losses.

The fire started Dec. 4 near the city of Santa Paula in Ventura County. The cause of the blaze remains under investigation.