Smoke from big wildfires burning east of the Cascade Range grounded helicopters and airplanes that have been battling the flames in Washington state.

The dense smoke also was causing respiratory problems for people far from the fire lines. In Spokane County, which has nearly 50,000 residents, the air quality was rated as unhealthy.

Crews battling a 262-square mile blaze near the town of Republic, south of the Canadian border, also were battling smoke as well as flames, fire spokesman Donnie Davis said.

"Everybody up here is rubbing their eyes," Davis said. "It's brutal."

A wildfire about 70 miles southwest in Okanogan — the largest blaze ever recorded in the state — grew to nearly 438 square miles and heavy smoke also grounded air resources, fire spokesman Rick Isaacson said.

"We're still socked in," Isaacson said. "There's maybe one mile of visibility."

On Thursday, Gov. Jay Inslee was scheduled to take an aerial tour of the wildfires and meet crews on the ground. So far, officials have counted 40 homes and 40 outbuildings destroyed by the blaze, Okanogan County Sheriff Frank Rogers said. The fire is about 17 percent contained by more than 1,300 firefighters.

Rogers said a forecast calling for highs in the 70s and rain in the next few days was good news.

"It is looking better for us," he said.

Several Western states are in the middle of a severe fire season with some 11,600 square miles scorched so far.

"You can imagine how stretched thin everybody is," said Dan Dallas, deputy incident commander of the Okanogan fire. "We're all working without the resources that in a normal year — which I don't think there is such a thing anymore — that we might have."

So many fires are burning in Washington state that officials summoned help from firefighters in Australia and New Zealand. They also got 200 U.S. troops from a base in Tacoma in the first such use of active-duty soldiers in nine years.

On Thursday, more than a dozen of the Australian firefighters were to begin working fighting the Okanogan area blazes.

The Oregon Military Department said soldiers also were ready to help battle a wildfire that has destroyed more than three dozen homes near John Day, about 150 miles east of Portland.

Fires also were burning in California, Montana and Idaho.

Schools reopened in a Southern California mountain community where crews were battling a small fire burning through timber near a popular ski resort.

Firefighters have held the blaze in the San Bernardino Mountains to 100 acres.