A fast-moving wildfire in Northern California destroyed several homes on Wednesday, while another blaze -- the largest the U.S. -- grew to more than 100,000 acres in Arizona.

The fires are among several burning across the western part of the country as dry conditions, low humidity and gusty winds increase fire danger in the region.

In California, CAL Fire said a fast-moving grass fire known as the Nelson Fire broke out around 11:49 a.m. in Thermalito, about 68 miles north of Sacramento.

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Fire officials said it scorched 95 acres, destroyed three homes and damaged two others.

The Nelson Fire in Butte County, California destroyed three homes and scorched some 95 acres on Wednesday.

The Nelson Fire in Butte County, California destroyed three homes and scorched some 95 acres on Wednesday. (CAL Fire/Butte Unit)

The Butte County Sheriff’s Office ordered evacuations for the neighborhood until firefighters were able to fully contain the blaze.

The Nelson Fire in Butte County, California destroyed three homes and scorched some 95 acres on Wednesday.

The Nelson Fire in Butte County, California destroyed three homes and scorched some 95 acres on Wednesday. (CAL Fire/Butte Unit)

The cause remains under investigation.

The Nelson Fire in Butte County, California destroyed three homes and scorched some 95 acres on Wednesday.

The Nelson Fire in Butte County, California destroyed three homes and scorched some 95 acres on Wednesday. (CAL Fire/Butte Unit)

The region remains under a red flag warning until Thursday night, due to winds up to 50 mph and low humidity, according to the National Weather Service (NWS).

In Arizona, where there are several wildfires, the largest blaze currently burning in the U.S. grew to more than 100,000 acres on Wednesday.

The "Bush Fire" in the Tonto National Forest is only 5 percent contained as of Thursday morning, with more than 500 firefighters involved in the battle.

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Residents in the Tonto Basin, Sunflower area, and the Apache Lake were ordered to evacuate, according to FOX10. Several state highways also closed as the blaze spread northeast of Phoenix.

Further south, officials said the Bighorn Fire burning in the Coronado National Forest near Tucson grew to some 23,892 acres and was at 40 percent containment as of Thursday morning.

The Bighorn Fire burning in the Coronado National Forest near Tucson has grown to some 23,892 acres and was at 40 percent containment as of Thursday.

The Bighorn Fire burning in the Coronado National Forest near Tucson has grown to some 23,892 acres and was at 40 percent containment as of Thursday. (Arizona State Forestry)

On Wednesday, gusty winds and high temperatures made conditions difficult for firefighters battling the blaze. Officials said "another day of challenging weather conditions" is expected for firefighters on Thursday.

Fire crews continued to see flames in the upper regions of Ventana and Espero canyons Wednesday as red flag warnings were in place for “strong gusty winds."

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Evacuation orders continued for Mount Lemmon, including Summerhaven and Mount Bigelow.

The Bighorn Fire burning in the Coronado National Forest near Tucson has grown to some 23,892 acres and was at 40 percent containment as of Thursday.

The Bighorn Fire burning in the Coronado National Forest near Tucson has grown to some 23,892 acres and was at 40 percent containment as of Thursday. (Arizona State Forestry)

New evacuation orders were ordered Thursday by the Pima County Sheriff's Department for the Willow Canyon area as the fire continues to spread.

Deputies were going door-to-door to make sure residents are out of their homes, according to officials.

Video taken from local resident Cecelia Fresh’s backyard in Saddlebrooke on Wednesday shows the plumes of smoke billowing from Mount Lemmon.

“We are on alert and ready to evacuate if told to go. It is a haunting feeling and certainly way too close to home,” Fresh told Storyful.

Wildfire danger begins to ease

Fire danger is relaxing for much of the West, except in southeast Arizona and southwest New Mexico.

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In those areas, breezy hot dry conditions persist on Thursday, and fire weather remains elevated in the region.

Fox News' Janice Dean contributed to this report.