WENATCHEE, Wash. (AP) — Firefighters battled stubborn blazes that kept residents from homes in Montana, Wyoming and Washington as authorities worried the weather could worsen the volatile situation.

High temperatures, lower humidity and greater instability increase the potential for fires to grow, said Ed Delgado, the national predictive services meteorologist for the National Interagency Fire Center in Boise, Idaho.

"Our biggest concern right now is existing fires," he said. "We're not expecting lightning over the next few days, although that doesn't alleviate the potential for human-caused fires, especially as we get into camping and hunting seasons."

Seven homes were destroyed and hundreds of people were evacuated near Casper, Wyo., where a wildfire burned almost 24 square miles. In western Montana, fire crews were struggling to control a blaze that prompted an evacuation order for 400 houses west of Hamilton.

In eastern Washington, a grass and sagebrush fire that ballooned from 11,000 acres to more than 60,000 — or 95 square miles — before winds died down was blamed for destroying three homes near Grand Coulee, a fire official said.

As winds eased, crews were hopeful they could gain ground on dozens of fires sparked by weekend lightning storms. But more evacuation orders were issued Tuesday as a wildfire moved into the hills west of Wenatchee, a fruit capital on the banks of the Columbia River.

More than 150 homes were evacuated as the fire burned about 140 miles east of Seattle. About 160 firefighters gathered to help fight the blaze, which covered 1,000 acres.

Only a shed has been lost near Wenatchee, and no injuries were reported at what appeared to be the most threatening of numerous lightning-sparked wildfires in the state.

In Montana, Sawtooth Fire spokesman Gregg DeNitto with the U.S. Forest Service said there was no word on when residents there might be allowed to return. The fire exploded over the past two days from just over 1 square mile to more than 6, although no houses were reported lost.

DeNitto said most threatened houses were a half-mile to one mile from the fire's edge.

An estimated 1,000 people live within the evacuated area, although Ravalli County Commissioner Suzy Foss said not all of them left. Of those who fled, most were staying with friends, relatives or acquaintances, Foss said.

Only a couple of residents spent the night at a Red Cross shelter set up in Hamilton for evacuees, DeNitto said.

Firefighters got help from the weather in Wyoming, where cooler temperatures and calmer winds bought time to put more people and equipment into action around two large fires. As many as 750 homes were threatened by the large wildfire near Casper. Some 400 people were evacuated from 150 homes.

In central Oregon, smoke settled in the town of Sisters for about six hours Tuesday as crews battled a forest fire on about 4,300 acres southwest of town. Sisters has about 2,000 residents and is a center for tourists and outdoor recreation.

The Oregon Department of Environmental Quality said atmospheric conditions — a temperature inversion — could mean poor air quality in the mornings through Saturday.

Residents of a subdivision west of Sisters have been warned that they might have to evacuate, but the fire has not yet advanced on populated areas.

Blazes have scorched more than 8.1 million acres across the West so far this year, up from the 10-year average of 6.1 million acres, according to the National Interagency Fire Center.

Other blazes burning across the West include:

— The Horsethief Canyon Fire, which has burned about 4 square miles south of the resort town of Jackson, Wyo. Firefighters were working to protect the town and the Jackson Hole valley's main communications towers from the blaze. About 1,000 residents have been warned to be prepared to leave in case the blaze gets too close.

— The Millie Fire about 20 miles south of Bozeman, Mont. The fire was threatening the city's water supply and 10 commercial buildings. Fire spokeswoman Jennifer Myslivy said the flames were stopped for now at the top of a ridge over South Cottonwood Canyon.

— As many as 80 fires sparked by lightning Saturday were burning along the east slopes of the Cascades in Washington state. Fifty-four homes were evacuated near Cashmere in front of a wildfire that has burned about 300 acres. Fire spokeswoman Connie Mehmel said the Cashmere fire was near other fires west of Wenatchee, but not expected to merge.

Another blaze north of Entiat forced the evacuation of 19 homes.

— A wildfire has burned 6½ square miles in a rugged area of the San Gabriel Mountains northeast of Los Angeles. The fire broke out over Labor Day weekend, sending out thousands of visitors from the Angeles National Forest.

___

Associated Press writers Matthew Brown in Billings, Mont., and Mead Gruver in Cheyenne, Wyo., contributed to this report.

"Our biggest concern right now is existing fires," he said. "We're not expecting lightning over the next few days, although that doesn't alleviate the potential for human-caused fires, especially as we get into camping and hunting seasons."

Seven homes were destroyed and hundreds of people were evacuated near Casper, Wyo., where a wildfire burned almost 24 square miles. In western Montana, fire crews were struggling to control a blaze that prompted an evacuation order for 400 houses west of Hamilton.

In eastern Washington, a grass and sagebrush fire that ballooned from 11,000 acres to more than 60,000 – or 95 square miles – before winds died down was blamed for destroying three homes near Grand Coulee, a fire official said.

As winds eased, crews were hopeful they could gain ground on dozens of fires sparked by weekend lightning storms. But more evacuation orders were issued Tuesday as a wildfire moved into the hills west of Wenatchee, a fruit capital on the banks of the Columbia River.

More than 150 homes were evacuated as the fire burned about 140 miles east of Seattle. About 160 firefighters gathered to help fight the blaze, which covered 1,000 acres.

Only a shed has been lost near Wenatchee, and no injuries were reported at what appeared to be the most threatening of numerous lightning-sparked wildfires in the state.

In Montana, Sawtooth Fire spokesman Gregg DeNitto with the U.S. Forest Service said there was no word on when residents there might be allowed to return. The fire exploded over the past two days from just over 1 square mile to more than 6, although no houses were reported lost.

DeNitto said most threatened houses were a half-mile to one mile from the fire's edge.

An estimated 1,000 people live within the evacuated area, although Ravalli County Commissioner Suzy Foss said not all of them left. Of those who fled, most were staying with friends, relatives or acquaintances, Foss said.

Only a couple of residents spent the night at a Red Cross shelter set up in Hamilton for evacuees, DeNitto said.

Firefighters got help from the weather in Wyoming, where cooler temperatures and calmer winds bought time to put more people and equipment into action around two large fires. As many as 750 homes were threatened by the large wildfire near Casper. Some 400 people were evacuated from 150 homes.

In central Oregon, smoke settled in the town of Sisters for about six hours Tuesday as crews battled a forest fire on about 4,300 acres southwest of town. Sisters has about 2,000 residents and is a center for tourists and outdoor recreation.

The Oregon Department of Environmental Quality said atmospheric conditions – a temperature inversion – could mean poor air quality in the mornings through Saturday.

Residents of a subdivision west of Sisters have been warned that they might have to evacuate, but the fire has not yet advanced on populated areas.

Blazes have scorched more than 8.1 million acres across the West so far this year, up from the 10-year average of 6.1 million acres, according to the National Interagency Fire Center.

Other blazes burning across the West include:

_ The Horsethief Canyon Fire, which has burned about 4 square miles south of the resort town of Jackson, Wyo. Firefighters were working to protect the town and the Jackson Hole valley's main communications towers from the blaze. About 1,000 residents have been warned to be prepared to leave in case the blaze gets too close.

_ The Millie Fire about 20 miles south of Bozeman, Mont. The fire was threatening the city's water supply and 10 commercial buildings. Fire spokeswoman Jennifer Myslivy said the flames were stopped for now at the top of a ridge over South Cottonwood Canyon.

_ As many as 80 fires sparked by lightning Saturday were burning along the east slopes of the Cascades in Washington state. Fifty-four homes were evacuated near Cashmere in front of a wildfire that has burned about 300 acres. Fire spokeswoman Connie Mehmel said the Cashmere fire was near other fires west of Wenatchee, but not expected to merge.

Another blaze north of Entiat forced the evacuation of 19 homes.

_ A wildfire has burned 6 1/2 square miles in a rugged area of the San Gabriel Mountains northeast of Los Angeles. The fire broke out over Labor Day weekend, sending out thousands of visitors from the Angeles National Forest.

___

Associated Press writers Matthew Brown in Billings, Mont., and Mead Gruver in Cheyenne, Wyo., contributed to this report.

Earlier on HuffPost:

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  • A house is engulfed in flames near Highway 48 and HW 38 junction east of Drumright, Okla., on Saturday, Aug 4, 2012. Emergency management officials have ordered evacuations of homes in several areas as wildfires burn across the state. The Oklahoma Department of Emergency Services says no injuries have been reported. (AP Photo/Tulsa World, Tom Gilbert)

  • Flames burn near Highway 48 and HW 38 junction east of Drumright, Okla., on Saturday, Aug. 4, 2012. Emergency management officials have ordered evacuations of homes in several areas as wildfires burn across the state. The Oklahoma Department of Emergency Services says no injuries have been reported. (AP Photo/Tulsa World, Tom Gilbert)

  • A home burns during a large wildfire Friday, Aug. 3, 2012 in Luther, Okla. A wildfire whipped by gusty, southerly winds swept through rural woodlands north and south of Oklahoma City on Friday, burning several homes as firefighters struggled to contain it in 113-degree heat. (AP Photo/The Oklahoman, Bryan Terry)

  • A house is engulfed in flames near Highway 48 and HW 38 junction east of Drumright, Okla., Saturday, Aug 4, 2012. While residents of one Oklahoma town sifted through their charred belongings Saturday to salvage what they could after a roaring wildfire that may have been deliberately set, residents in two other towns were being ordered to evacuate their homes. (AP Photo/Tulsa World Tom Gilbert)

  • Kellyville firefighter Levi Stephens fights a grassfire in Kellyville, Okla., near West 151st and the Turner Turnpike, Saturday, Aug 4, 2012. Emergency management officials have ordered evacuations of homes in several areas as wildfires burn across the state. The Oklahoma Department of Emergency Services says no injuries have been reported. (AP Photo/Tulsa World, Tom Gilbert)

  • Kellyville firefighter Levi Stephens fights a grassfire in Kellyville, Okla., near West 151st and the Turner Turnpike on Saturday, Aug 4, 2012. Emergency management officials have ordered evacuations of homes in several areas as wildfires burn across the state. The Oklahoma Department of Emergency Services says no injuries have been reported. (AP Photo/Tulsa World, Tom Gilbert)

  • Structures are engulfed in flames near Highway 48 and HW 38 junction east of Drumright, Okla., on Saturday, Aug 4, 2012. Emergency management officials have ordered evacuations of homes in several areas as wildfires burn across the state. The Oklahoma Department of Emergency Services says no injuries have been reported. (AP Photo/Tulsa World, Tom Gilbert)

  • Rebecca Kolar stands at the entrance to the three bedroom, brick home at 908 S. Dogwood Street where she and her husband, Douglas lived with their two children for 13 years before fire destroyed it, Saturday, Aug. 4, 2012 in Luther, Okla. While residents of one Oklahoma town sifted through their charred belongings Saturday to salvage what they could after a roaring wildfire that may have been deliberately set, residents in two other towns were being ordered to evacuate their homes. The fire near Luther, which is about 25 miles northeast of Oklahoma City, destroyed nearly five dozen homes and other buildings before firefighters were able to gain some measure of control Saturday.(AP Photo/The Oklahoman, Jim Beckel) TABLOIDS OUT

  • Tracy Streeper hugs five year-old grandson Jesse, as they stand on the north side of Streeper's destroyed home, Saturday, Aug. 4, 2012 in Luther, Okla. While residents of one Oklahoma town sifted through their charred belongings Saturday to salvage what they could after a roaring wildfire that may have been deliberately set, residents in two other towns were being ordered to evacuate their homes. The fire near Luther, which is about 25 miles northeast of Oklahoma City, destroyed nearly five dozen homes and other buildings before firefighters were able to gain some measure of control Saturday.(AP Photo/The Oklahoman, Jim Beckel) TABLOIDS OUT

  • A house is engulfed in flames near Highway 48 and HW 38 junction east of Drumright, Okla., on Saturday, Aug 4, 2012. Emergency management officials have ordered evacuations of homes in several areas as wildfires burn across the state. The Oklahoma Department of Emergency Services says no injuries have been reported. (AP Photo/Tulsa World, Tom Gilbert)

  • Victoria Landavazo holds youngest child, Axel, 1 year old, while wiping tears after arriving with other members of her family to see for the first time what the wildfire had done to their home, Saturday, Aug. 4, 2012 in Luther, Okla. While residents of one Oklahoma town sifted through their charred belongings Saturday to salvage what they could after a roaring wildfire that may have been deliberately set, residents in two other towns were being ordered to evacuate their homes. The fire near Luther, which is about 25 miles northeast of Oklahoma City, destroyed nearly five dozen homes and other buildings before firefighters were able to gain some measure of control Saturday.(AP Photo/The Oklahoman, Jim Beckel) TABLOIDS OUT

  • Flames and smoke threaten structures near Highway 48 and HW 38 junction east of Drumright, Okla. Emergency management officials have ordered evacuations of homes in several areas as wildfires burn across the state. The Oklahoma Department of Emergency Services says no injuries have been reported. (AP Photo/Tulsa World, Tom Gilbert)

  • Area firefighters fight a grass fire east of 120th at Cemetery Road on Friday, Aug. 3, 2012, east of Norman, Okla. A wildfire stirred by high winds sweeping through rural woodlands just south of the Oklahoma City area has set at a number of homes on fire. (AP Photo/The Oklahoman, Steve Sisney)

  • A helicopter drops water on a large grass fire east of 120th near Cemetery Road on Friday, Aug. 3, 2012, east of Norman, Okla. A wildfire stirred by high winds sweeping through rural woodlands just south of the Oklahoma City area has set at a number of homes on fire. (AP Photo/The Oklahoman, Steve Sisney)

  • Flames leap into the air as area firefighters fight a wildfire on Cemetery Road east of 120th on Friday, Aug. 3, 2012, east of Norman, Okla. A wildfire stirred by high winds sweeping through rural woodlands just south of the Oklahoma City area has set at a number of homes on fire. (AP Photo/The Oklahoman, Steve Sisney)

  • Ruth Hood hugs her dog Punky while waiting a gas station at SE 108th and Hwy 9 after evacuating her home near SE 132nd and Hwy 9 as a wildfire burns through Cleveland County near Norman, Okla., Friday, Aug. 3, 2012. A wildfire stirred by high winds sweeping through rural woodlands just south of the Oklahoma City area has set at a number of homes on fire. (AP Photo/The Oklahoman, Nate Billings)

  • Vin Bayne pours water for his pets while waiting at a gas station at Hwy 9 and SE 108 Ave. after evacuating his home as a wildfire burns through Cleveland County near Norman, Okla., Friday, Aug. 3, 2012. A wildfire stirred by high winds sweeping through rural woodlands just south of the Oklahoma City area has set at a number of homes on fire. (AP Photo/The Oklahoman, Nate Billings)

  • From left, Gayland Cannon, Eugene Hacker and Ron Ross wait at a gas station at SE108 and Hwy 9 after evacuating their homes in the area of SE 132nd and Cedar Lane as a wildfire burns through Cleveland County near Norman, Okla., Friday, Aug. 3, 2012. A wildfire stirred by high winds sweeping through rural woodlands just south of the Oklahoma City area has set at a number of homes on fire. (AP Photo/The Oklahoman, Nate Billings)

  • A mobile home burns at South Cedar and South 8th St., during a large wildfire, Friday, Aug. 3, 2012 in Luther, Okla. A wildfire whipped by gusty, southerly winds swept through rural woodlands north and south of Oklahoma City on Friday, burning several homes as firefighters struggled to contain it in 113-degree heat. (AP Photo/The Oklahoman, Sarah Phipps)

  • A smoke surrounds home during a large wildfire Friday, Aug. 3, 2012 in Luther, Okla. A wildfire whipped by gusty, southerly winds swept through rural woodlands north and south of Oklahoma City on Friday, burning several homes as firefighters struggled to contain it in 113-degree heat. (AP Photo/The Oklahoman, Sarah Phipps)

  • A home burns during a large wildfire Friday, Aug. 3, 2012 in Luther, Okla. A wildfire whipped by gusty, southerly winds swept through rural woodlands north and south of Oklahoma City on Friday, burning several homes as firefighters struggled to contain it in 113-degree heat. (AP Photo/The Oklahoman, Sarah Phipps)

  • Bill Ragle walks past the remains of his home that was destroyed by a wildfire in Mannford, Okla., Sunday Aug. 5, 2012. (AP Photo/Tulsa World Mike Simons)

  • In this Saturday, Aug. 4, 2012 photo, flames engulf a house near Highway 48 and HW 38 junction east of Drumright, Okla. The Oklahoma Department of Emergency Services says no injuries have been reported. (AP Photo/Tulsa World, Tom Gilbert)

  • Casey Strahan, lower left, and Logan Renner, 17, look at the reamins of their homes, Saturday, Aug. 4, 2012 in Luther, Okla. While residents of one Oklahoma town sifted through their charred belongings Saturday to salvage what they could after a roaring wildfire that may have been deliberately set, residents in two other towns were being ordered to evacuate their homes. The fire near Luther, which is about 25 miles northeast of Oklahoma City, destroyed nearly five dozen homes and other buildings before firefighters were able to gain some measure of control Saturday.(AP Photo/The Oklahoman, Jim Beckel) TABLOIDS OUT