Firefighters in Northern California have made progress on a stubborn blaze west of Sacramento, officials said on Thursday, allowing some residents to return to their homes after they were evacuated.
In Colorado, meanwhile, firefighters were still battling eight major blazes that have burned over 140,000 acres and destroyed more than 100 homes, while authorities have arrested a person suspected of starting the largest blaze in that drought-stricken state.
The Northern California fire "burned throughout the night with little recovery from the relative humidity," the California Department of Forestry and Fire Protection said in a statement. "The weather will become hotter and drier into the weekend and fire growth potential remains high."
The so-called County Fire had consumed 86,000 acres (35,000 hectares) of grass, brush and dense scrub oak as of early Thursday, Cal Fire said.
Some residents were allowed to return home after being evacuated. Cal Fire said the fire was threatening 990 structures, down from 1,500 previously under threat. No civilians or firefighters have been hurt, and no structures have been damaged so far, officials said.
A force of almost 3,500 firefighters widened its containment lines to 30 percent, up from 27 percent late on Wednesday, Cal Fire said.
Firefighters have been challenged by strong wind gusts, steep inaccessible terrain and dry vegetation as they have fought the unrelenting wildfire that began on Saturday.
The United States is experiencing an unusually active fire season, with the risk considered well above normal for many Western states, according to federal forecasters.
Temperatures in the area of the California blaze will reach close to 90 degrees Fahrenheit (32 Celsius) on Thursday, the National Weather Service said, warning of widespread haze and smoke.
Wildfires have burned through nearly 2.5 million acres in the United States from Jan. 1 through Monday, well above an average of about 2.3 million acres for the same period over the last 10 years, according to the National Interagency Fire Center.
In Colorado, authorities ordered residents to leave a neighborhood near Aspen as the Lake Christine Fire grew quickly due to erratic winds, dry fuel and low relative humidity.
"The fire grew so much that an accurate size estimate is not yet available," the Eagle County Sheriff's Office said on Thursday. "Today's predicted weather includes increased relative humidity, which should help moderate fire behavior."
The largest of eight major blazes in Colorado, the Spring Fire, has consumed 95,739 acres in the south of the state, destroying more than 100 homes, forcing evacuations of several communities and closing a road.
The Spring Fire, the second-largest fire on record in Colorado, was just 5 percent contained, officials said.
Jesper Joergensen, a 52-year-old Danish national, is being held on first-degree arson charges, the Costilla County Sheriff's Office said. The suspect is in the country illegally and may face deportation, police said.
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