Crews facing adverse weather forecasts rushed to bolster protective lines around blazes that have scorched tens of thousands of acres in the Northern Rockies, while firefighters in Oregon worked to corral a range fire that forced a kids' science camp to evacuate.
Fire conditions rose to critical Thursday as steady winds fanned several blazes and scattered storms threatened to spark new ones across Montana, north central Idaho and northwest Wyoming.
The pattern of hot, dry weather and afternoon storms was expected to recur daily for at least several more days, keeping the fire risk high.
"Any time you have storms, it's not just the lightning that's the problem, it's the wind they're producing," said National Weather Service meteorologist Joe Lester. "It's going to be an issue we have to keep watching through the weekend and into early next week."
In central Oregon, a lighting storm started about 150 fires, one of which grew to 10,000 acres. About 55 children and a dozen staff members were forced to leave the Hancock Field Station outside Fossil, Ore., because of the blaze Wednesday night.
The camp staff was prepared and took the kids to a campground outside Fossil, where they spent the night in tents, said Andrea Middleton, spokeswoman for the Oregon Museum of Science and Industry. The kids are to camp out at another campground Thursday, then return to Hancock Friday.
Crews gained ground on some blazes Thursday, including a 24,570-acre complex of fires on the Northern Cheyenne Reservation in southeastern Montana.
An estimated two dozen homes and other structures were threatened by the five wildfires comprising the complex near Lame Deer, Mont. No evacuations had been ordered, and the fire is about 60 percent contained.
Fire information officer Katie Knotek said crews were focused on strengthening the protective line around the fire, but were prepared to go on the attack if wind revives the blazes or lightning sparks new ones.
About 475 people were working on the blaze, and fire officials don't expect to request any more in an effort to share resources with fires across the state.
Another nearby complex, the 39,700-acre Diamond fires burning in grass and timber south of Ashland, threatened more than a dozen homes and outbuildings, including the post office in Otter.
Crews saved one house by digging bulldozer lines to steer the blaze around the structure, said fire information officer Pat McKelvey. He said others remained at risk as the fire spread through the afternoon.
"That acreage is going to go up. I watched a lot of it get gobbled up today," McKelvey, adding that although the fire had grown, winds shifted it away from the post office, a wooden structure.
Bryan Henry, a meteorologist for the Northern Rockies Coordination Center, said lightning was expected Thursday and Friday over western Montana and northern Idaho, and over southwestern Montana on Saturday.
If those storms don't produce much precipitation, new fires are likely to start.
Temperatures in those areas are expected to stay in the 90s through Friday, which is about 10 degrees above normal for this time of year.
In western Montana, a complex of wildfires that surged across the Continental Divide from Idaho earlier this week grew Thursday to 22,097 acres.
The Ravalli County Sheriff's Office told residents in about 50 homes near Painted Rocks State Park to be ready to leave on short notice. The blaze was burning in steep terrain that had not been hit by fire in more than a century.
Firefighters were preparing to protect homes and buildings along the West Fork of the Bitterroot River drainage southwest of Darby.
The complex has so far burned 11,344 acres in the Bitterroot National Forest and 10,753 acres in the Salmon-Challis National Forest in Idaho.
Near Bonner, Mont., the wind picked up Thursday afternoon and stoked a 2,100-acre wildfire that had been relatively calm all morning as it burned in steep, rugged terrain near Bonner.
But the wind also helped firefighting efforts by clearing out a weather inversion that had prevented helicopters from taking to the air and dropping water on the blaze all morning, fire information officer Tom Rhode said.
Firefighters have built a line and laid hoses to protect dozens of nearby homes, he said.
"They're not necessarily out of danger, but what I can tell you is the fire activity has moved away from there," he said.
In northern Wyoming, a Wednesday night thunderstorm thwarted attempts to keep a fire from crossing into Montana and threatening several rural subdivisions south of Red Lodge.
The fire had grown to more than 5,700 acres by Thursday afternoon and crews were trying to stop the fire's northward march into the Custer National Forest where there are summer cabins.
Six other fires were burning elsewhere in Wyoming, including one north of Gillette that had charred about 4,000 acres. A 14,485-acre fire west of Wheatland and an 800-acre fire west of Dubois were fully contained by Thursday afternoon.
After overnight lightning strikes, Idaho's Salmon-Challis National Forest reported at least six new fires Thursday.
"Most of them are pretty remote," said Jesse Bender, a spokeswoman. "They're all small in size so we're staffing them to get them put out as quickly as possible."
And after lightning strikes hit the Clearwater and Nez Perce national forests, fire officials dispatched 16 smokejumpers to a one-square-mile blaze. There were at least three other new fires on the forests, all less than an acre.
Meanwhile, a 20-person crew aided by a light helicopter was keeping an eye on a 3,800-acre blaze on the remote Red River Ranger district, about 20 miles east of Elk City.
Associated Press writers Matt Volz in Helena, Bob Moen in Cheyenne, Wyo., and John Miller in Boise, Idaho, contributed to this report.