Wildfire smoke continued to spread in the western U.S. Monday as dozens of large fires burned across the country, with the largest raging in California, officials said.

Dangerous fire weather notices, also called red flag warnings, and air quality alerts were also in place Monday across Idaho, Wyoming and Oregon, urging residents to prepare for gusty winds and low humidity that "can lead to rapid growth and very high intensity of any new or existing fires," the National Weather Service said. As of Sunday, 103 large fires were being targeted by firefighters across the U.S., according to the National Interagency Fire Center.

In northeast Oregon, fires have led to highway closures, affecting local businesses like Tyler Fouts' Blue Mountain Fine Art studio in Baker City. Semi-trucks carrying bronze and sand Fouts uses to make sculptures haven't been able to make deliveries, he told USA TODAY.

"They seem to open and close the highway off an on," said Fouts, 65, who has been in Baker City for 20 years. "I'm just hoping it goes away."

Fouts said Baker City is about 20 miles north of the nearest fire, and the community hasn't been told to evacuate yet. Over the weekend, evacuations were in effect for over 20 fires nationwide, according to the National Interagency Fire Center.

Massive fires in California

Thousands of firefighters responded over the weekend to the Park Fire, which started Wednesday after authorities say a man pushed a burning car into a gully in Chico and then fled. Ronnie Stout, 42, accused of starting the Park Fire, which has grown to become the largest in the state this year, is due in court Monday, according to a Butte County District Attorney news release.

Live footage of the wildfire on California's Department of Forestry and Fire Protection website Monday showed flames glowing atop hillsides, creating multiple streams of dense gray smoke near Colby Mountain in Tuolumne County.

State officials said Sunday night the fire is 12% contained and burning more than 360,000 acres near Paradise, California, a town that saw severe damage from wildfires in 2018.

A handful of other fires in California are together burning more than 82,000 acres, state officials said, with the largest of the group spreading rapidly in recent days. The blaze, called the Borel Fire, is "expected to be, once again, very extreme," the state's Department of Forestry and Fire Protection said late Sunday.

Oregon wildfires

In Oregon, where officials say lightning has sparked fires, the body of a missing airplane pilot was found Friday after his plane went down while battling a fire.

In northeast Oregon, state officials said Sunday more fire responders are being sent to tackle blazes near the town of Wallowa, where five fires converged over the weekend, the Wallowa County Chieftain reported.

"The team is being ordered in anticipation of unfavorable weather in the area later in the week," the Oregon Department of Forestry said on their Facebook page Sunday night.

Smoke outlooks across five countries in eastern Oregon said "unhealthy" air conditions are expected to persist Monday and Tuesday, after a weak cold front moves through the area, according to the U.S. Interagency Wildland Fire Air Quality Response Program.

“You do get concerned that it will get worse, that the smoke will get worse, because at some point it does get really unhealthy to be outside," said Fouts, adding that some of his friends experience headaches and allergy-like symptoms from wildfire smoke.

Further west, La Pine, Oregon, recently registered an Air Quality Index of 233, breaking into the "very unhealthy" category, according to state air quality officials.

'Critical' fire conditions in Utah

The National Weather Service said much of Utah will face weather conditions through Tuesday that can easily cause more fires, including wind gusts up to 30 mph and humidity as low as 5%.

The conditions will be the most dangerous across southern and central Utah through Monday, the weather service said, before shifting to higher elevations in northern Utah Tuesday.

Wyoming, Idaho fires

In Wyoming, where a plane crash sparked a wildfire Friday, several red flag warnings are in effect until Tuesday, when wind gusts are expected to subside and possibly allow for clear conditions, the National Weather Service said.

Seven people died during the plane crash that happened north of the town of Gillette, in Campbell County. By Saturday afternoon, firefighters had contained the fire caused by the accident to 38 acres, according to a Campbell County Fire Department press release.

As of Monday, there were at least three active fires still burning in the county, according a national wildfire tracker, and Campbell County Public Information Officer Leslie Perkins told USA TODAY there was no update available on the fire caused by the plane crash.

In Idaho, which in July has seen nearly triple the number of wildfires compared to June, roads and trails northeast of Boise were closed Monday, according to Idaho Fish and Game. Most of the state's active fires are in its northern half, or panhandle. One of the largest fires in the state is burning near the town of Fish, Idaho.

The weather service also issued forecasts for Idaho saying fire-spurring winds could decrease overnight Monday is some areas, while elsewhere, warm temperatures through Tuesday could lead to "extreme fire behavior."