LAME DEER, Mont. (AP) — Wildfires in Montana threatened rural towns and ranchland Friday and victims of a California blaze returned to their incinerated community, even as the U.S. West faced another round of dangerous weather and smoke pollution fouled the air.

Firefighters and residents have scrambled to save hundreds of homes as flames advance across the Northern Cheyenne Indian Reservation in southeastern Montana.

An evacuation order was lifted Friday morning for about 600 people in and around the town of Ashland, just east of the reservation, signaling progress on the blaze that had burned out of control since Sunday.

But the fire was still burning near the tribal headquarters town of Lame Deer, where a mandatory evacuation remained in place and a second fire was threatening from the opposite direction.

Smoke from the blazes grew so thick Friday morning that the health clinic in Lame Deer was shut down after its air filters could not keep up with the pollution, Northern Cheyenne Tribe spokesperson Angel Becker said.

The evacuation order for the town will remain in place until the fire is under better control and the smoke clears, to protect the elderly and people with asthma and other conditions, Becker said.

“Lame Deer is sitting in between a couple ravines so when you get socked in it just sits here, and that’s not good for elders,” she said.

More than 100 large fires were burning across the U.S. West with dozens more burning in western Canada. Th e smoke drove air pollution levels to unhealthy or very unhealthy levels in portions of Montana, Idaho, Oregon Washington and Northern California, according to Environmental Protection Agency air quality monitoring.

An air quality alert covering seven Montana counties warned of extremely high levels of small pollution particles found in smoke, which can cause lung issues and other health problems if inhaled.

The fires near Lame Deer combined have burned 275 square miles (710 square kilometers) this week, so far sparing homes but causing extensive damage to pasture lands that ranchers depend on to feed their cows and horses.

As the blaze raged across rugged hills and narrow ravines, tribal member Darlene Small helped her grandson move about 100 head of cattle to a new pasture, only to relocate them twice more as the flames from the Richard Spring fire bore down.

“They’ve got to have pasture where there’s water. If there’s no water, there’s no good pasture,” Small said. Particularly hard hit were some ranchers already depending on surplus grass after a fire burned them off their normal pasture last year, she said.

Gusts and low humidity were creating extremely dangerous conditions as flames devoured brush, short grass and timber, fire officials said.

The same conditions turned California's Dixie Fire into a furious blaze that last week burned down much of the small town of Greenville in the northern Sierra Nevada. The fire that began a month ago has destroyed 550 homes.

Residents were trying to cope with the magnitude of the losses.

“Everything that I own is now ashes or twisted metal. That’s just all it is,” said Greenville resident Ken Donnell, who escaped with the clothes on his back.

The fire had ravaged more than 800 square miles (well over 2,000 square kilometers) — an area larger than the city of London — and continued to threaten more than a dozen rural and forest communities.

Containment lines for the fire held overnight, but it was just 31% surrounded and fire officials warned temperatures in Northern California would again reach triple digits Friday.

Isolated thunderstorms in the Sierra Nevada could bring some moisture, but also gusty and erratic winds that could help spread the fire, California Department of Forestry and Fire Protection officials said. Lightning could spark new blazes even as crews try to surround a number of other forest fires ignited by lightning last month.

Hot, dry weather with strong afternoon winds also propelled several fires in Washington state and similar weather was expected into the weekend, fire officials said.

In southeastern Oregon, two new wildfires started by lightning Thursday near the California border were spreading through juniper trees and sagebrush.

Gov. Kate Brown declared an emergency for one of the fires to mobilize crews and other resources to the area of ranches, rural subdivisions and RV parks about 14 miles (23 kilometers) from the small town of Lakeview.

The blaze grew from a lightning strike to 11 square miles (28 square kilometers) in less than 24 hours, said Tamara Schmidt, a U.S. Forest Service spokeswoman.

Authorities Thursday evening ordered the evacuation of an RV park that stood in the path of the Oregon's Patton Meadow Fire.

The fires are near the area torched Oregon's Bootleg Fire which started July 6 and burned an area more than half the size of Rhode Island before crews gained the upper hand. The fire is not yet fully contained and was the nation’s largest until being eclipsed by the Dixie Fire.

Triple-digit temperatures and bone-dry conditions in Oregon, enduring a third day of extreme heat, could increase fire risks through the weekend.

In Montana, days of swirling winds spread flames in all directions, torching trees and blowing embers that flew across an arid landscape.

The Richard Spring fire was within about 2 miles (3.2 kilometers) of the eastern edge of the community of Lame Deer, while a smaller fire was about 5 miles (8 kilometers) to the west, said fire spokesperson Jeni Garcin.

After a brief break in the weather that brought cooler temperatures Thursday, it’s expected to start heating up again, reaching the 90s by Saturday and staying hot through Monday. Officials say that will dry out grasses and other fuels and make them more susceptible to burning.

Climate change has made the U.S. West warmer and drier in the past 30 years and will continue to make the weather more extreme and wildfires more destructive, according to scientists.

More than 6,000 square miles (almost 15,000 square kilometers) have been burned in the U.S. so far this year. That's well ahead of the amount burned by this point last year, but below the 10-year average, according to the National Interagency Fire Center.

Parts of Europe also are burning including in Greece, where where a massive wildfire has decimated forests and torched homes, and was still smoldering 10 days after it started.

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Eugene Garcia in Greenville, California, Olga R. Rodriguez in San Francisco and Gillian Flaccus in Portland contributed to this report.