Oct. 16 (UPI) -- Colorado's Cameron Peak fire, the largest in the state's history, has burned nearly 170,000 acres as more than 1,110 firefighters attack the blaze with weather conditions expected to worsen over the weekend.
The fire, which ignited Aug. 13 about 108 miles northwest of Denver, has grown to 167,153 acres and was 56% contained by Thursday evening, officials said, adding 1,119 were battling the blaze.
"Firefighters had a successful day on the Cameron Peak fire today, directly attacking the fire where it was safe to do so," officials said on the fire's Facebook page. "Air resources, including three large air tankers and four type-1 helicopters, were very busy."
A Red Flag Warning indicating critical fire weather conditions of low humidity and strong winds has been issued for the area from noon Friday to 6 p.m. Saturday, the National Weather Service said.
"With more mountain wave activity and another strong and dry cold front forecast for the Friday night in Saturday period, expect winds to become strong again with poor recoveries leading into low daytime humidity Saturday," officials said in an update.
The Larimer County Sheriff's Office upgraded an evacuation warning to order on Wednesday, instructing residents and businesses to leave the area immediately.
"Do not delay leaving to gather belongings or make efforts to protect your home or business," the order said.
Gov. Jared Polis tweeted Wednesday that the Cameron Peak fire had become the largest fire in the state's history, surpassing the Pinch Gulch fire that had burned 139,007 acres between July and September and the Hayman fire of 2002, which had burned about 138,000 acres.
"All Colorado and the world cheer on our brave firefighters in their efforts to protect population centers and contain the fire," he said.
Officials said its cause was under investigation but it was expected to be contained by Nov. 8.