Firefighters gained ground on a number of wildfires across the West but struggled in southern Idaho, where winds fanned a fast-moving blaze across 235 square miles of sagebrush and dry grass, threatening a handful of homes, authorities said Monday.

More firefighters were headed to the Idaho wildfire that was sparked by a Saturday lightning storm and had spread to 150,000 acres. The fire was threatening six homes in the Castleford area, west of Twin Falls, said Bureau of Land Management spokeswoman Kyli Gough.

Firefighters made progress in California, Utah, Wyoming Colorado and Montana, where the country's biggest wildfire is burning, according to the National Interagency Fire Center.

The 250,000-acre Ash Creek fire in southeastern Montana was 90 percent contained and expected to be fully contained later Monday.

Crews have been battling the spread of the lightning-caused wildfire through the Northern Cheyenne Indian Reservation and Custer National Forest since June 25. Also burning in southeastern Montana was the Taylor Creek fire, which has charred more than 62,000 acres about 12 miles southeast of Fort Howes. That fire was 65 percent contained.

In northern California, a wildfire burning near a main highway in the eastern Sierra Nevada was more than 85 percent contained.

The 1,103-acre blaze west of Highway 395 was spotted Saturday and briefly threatened about 300 homes but had no active flames early Monday. Crews were concentrating on dousing hotspots to avoid flare-ups, with the Inyo County area expected to see strong winds and high temperatures early this week.

Cooler temperatures and rain helped firefighters gain the upper hand on Utah's largest active wildfire. The 108,000-acre Clay Springs fire in Millard and Juab counties was 85 percent contained, officials said. The weather helped crews move a string of other wildfires in Utah closer to containment.

In southern Idaho, about 200 firefighters were working to contain the fast-moving Kinyon Road fire that was among the largest in the nation.

More firefighters were expected to take over management of the blaze, bringing the total number of personnel to 275. Crews had hoped to contain the blaze late Sunday, but a storm cell moved in and brought some rain and increased winds.

The region's grass and sagebrush have provided readily available fuel for the blaze, which was 25 percent contained.

"The wind has been a big factor," Gough said. "With these light fuels being the way they are, even a small amount of wind can pick up the fire and move it pretty quickly."

Paramedics in Castleford transported a 56-year-old man to a Twin Falls hospital late Sunday due to heat-related illness, said Gough, who did not know the man's condition.

Rain and cooler weather helped the fight against wildfires burning in Wyoming.

The largest of those fires was roughly 150 square miles and burning northwest of Wheatland. Rainfall over the weekend allowed firefighters to attack parts of the Arapaho fire that were previously inaccessible, and it was 75 percent contained.

In Colorado, wet conditions made Gov. John Hickenlooper confident enough to lift a statewide fire ban he ordered last month. Amid recent widespread rainfall, extreme fire conditions eased in all of Colorado's 64 counties.

The rainfall, however, brought its own problems. One of the main highways to Leadville was closed after the road washed out following heavy rains that also caused a mudslide in northern Colorado.

In Washington state, the U.S. Forest Service said a 675-acre wildfire between Entiat and Chelan was human-caused. The fire began Thursday and grew Saturday as hot temperatures and low humidity arrived in the region. However, the blaze in Navarre Coulee was 75 percent contained after burning areas of steep terrain with hazards from rolling rocks.