California firefighters are slowly making progress in containing the largest wildfire that the state has experienced this year, the U.S. Forest Service said.

Fire crews continued to battle against the Beckwourth Complex fire, which is a combination of two fires burning through the Plumas National Forest. Authorities noted that the blaze has already gone through nearly 90,000 acres as of Monday night.

Massive California Wildfires

The Dotta Fire, which was sparked by lightning, has been burning since June 30. Authorities have reported that the blaze was 99% contained. However, they noted that it is the smaller of the two fires, only burning about 670 acres.

More lightning struck two days after the start of the Dotta Fire, which resulted in the Sugar Fire, which has since burned down more than 89,000 acres. As of Monday night, fire crews reported the blaze was 23% contained.

The agency said that the factors which contributed to the “extreme fire behavior” included dry, unstable winds and low humidity. These conditions provided an ideal environment for wildfires to spark and expand. Authorities noted that the severe temperatures exceeding 100 degrees also contributed to the incidents.

Authorities are ordering residents in Plumas, Lassen and Washoe counties to evacuate their homes after the wildfire has already consumed at least 20 residences in the area. The incident comes as the country’s largest fire in Oregon continues to burn, running through more than 153,000 acres so far.

“We are seeing doubling in size of the fire every 24 hours. Basically, every ember that falls will start a new fire,” Oregon State Fire Marshal Gert Zoutendijk said regarding the Bootleg Fire on Saturday, CBS News reported.

Fire crews were able to limit the spread of the Bootleg Fire from expanding another 5,000 acres on Monday, a few days after the massive blaze doubled in size. The Forest Service said the cause of the wildfire, which began on July 6, was still unknown.