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, said Northern Cheyenne Tribe spokesperson Angel Becker.

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. “We’re trying to keep everybody out so we don’t have the potential for more sickness or anything else that’s going to bring down immune systems.”

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 the 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. An extreme drought that’s blanketing the West has made matters worse by stunting vegetation untouched by fire.

“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 some 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 just the clothes on his back.

Donnell said he was heart-broken but “by God, I’m gonna smile. Because you know, it just makes things a little bit better and a little bit better right now is a lot.”

Sam Prentice, a firefighter for the USDA Forest Service battled the flames in Greenville on Aug. 5, when the town was leveled. He was not optimistic on Greenville’s ability to rebuild.

“Essentially it starts to become an archeology site — kind of a testament to the fire era that we’re in right now,” said Prentice. “It’s daunting.”

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, bringing potentially critical fire weather in the afternoon.

Isolated thunderstorms in the Sierra Nevada could bring some moisture, but also gusty and erratic winds that could help spread the fire, Cal Fire officials said. Lightning could spark new blazes even as crews try to surround a number of other forest fires that were 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 Montana, days of swirling winds spread flames in all directions, torching trees and blowing embers that flew across a dry landscape.

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

Of most immediate concern were areas southeast of the town, where homes in a rural area were threatened. Fire engines were posted in that area to provide protection if flames threatened houses, Garcin said.

With 40-foot (12-meter) flames visible from parts of Lame Deer overnight Wednesday, firefighters worked urgently to keep the blaze from destroying houses.

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, and Olga R. Rodriguez in San Francisco contributed to this report.