Clouds rolled across eastern California on Tuesday, giving firefighters hope for moisture to help them battle huge wildfires in the parched Sierra foothills, officials said.

However, the arriving weather front also carried a threat of wind and lightning that could spread flames and start new fires.

"Anything can happen with huge winds that come up," U.S. Forest Service spokeswoman Nancy Upham said.

Damper, cooler weather already had helped fire crews in South Dakota, but a continuing heat wave was expected to challenge firefighters dealing with fast-moved blazes in other Western states.

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Cooler temperatures and lighter wind in Northern California had allowed crews to make significant progress toward taming a 35,000-acre fire in the Inyo National Forest. The state's largest blaze, sparked by lightning on Friday, was 80 percent contained Tuesday after destroying six homes and closing down trails into a popular wilderness area north of Mount Whitney.

On Sunday, the fire temporarily forced 200 residents of Independence to leave their homes and closed down a long stretch of Highway 395. Eleven firefighters had suffered minor injuries, U.S. Forest Service spokeswoman Pam Bierce said.

Along the coast, firefighters lost some ground in the Los Padres National Forest as flames there chewed through brittle brush and trees unburned in four decades. The 9,500-acre fire, which was 30 percent contained, threatened more than 20 unoccupied cabins in Zaca Lake Retreat and the historic Manzana Schoolhouse.

Firefighters in Nevada faced another day of triple-digit temperatures, choking smoke and difficult terrain Monday as they confronted lightning-sparked wildland fires that blackened more than 245 square miles across northern Nevada but spared dozens of homes.

A 20,500-acre fire burned into the back yards of a residential area of Winnemucca, about 170 miles east of Reno, but stopped short of the houses. An electrical substation and a handful of outbuildings were destroyed.

Weather was cool and cloudy Tuesday in the southwest corner of South Dakota and crews expected to make significant progress on a wildfire near Hot Springs that killed a homeowner and destroyed 30 houses. The blaze had covered an additional 900 or so acres since late Monday, bringing the total to more than 15 square miles or 9,888 acres. It was 20 percent contained Tuesday morning.

"We're starting to gain a hold on this thing," Joe Lowe, state wildland fire suppression coordinator, told many of the 500 firefighters near Hot Springs on Tuesday. "It's not over yet but we're getting close."

Wildfires kept Kitt Peak National Observatory in southern Arizona closed Monday and three small communities in the northern part of the state remained under evacuation orders as gusty winds and hot weather hampered firefighters' efforts. At least nine fires larger than 100 acres were burning across the state, although most were in remote areas and not affecting people.

In central Utah, progress was being made as crews headed out Tuesday to fight the biggest wildfire in state history. The burned area increased to 469 square miles Tuesday, but that was a gain of only about 11,000 acres from Monday, authorities said. The fire about 120 miles south of Salt Lake City was 10 percent contained.

Fire officials warned that extreme fire weather was expected to continue for the next several days.

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