(Updates throughout with firefighters mounting assault on fire)
By Laura Zuckerman
SALMON, Idaho, Aug 18 (Reuters) - Firefighters mounted on Sunday an all-out ground and air attack on an Idaho wildfire that has forced the evacuation of some 2,250 homes and threatened the world-class ski resort of Sun Valley, where snow-making water cannons were used to keep the flames at bay.
The fire raging across parched sagebrush, grasslands and pine forests near high-end developments in the Sun Valley area has consumed 101,000 acres (41,000 hectares) and destroyed one home and seven other buildings since lightning sparked the blaze on Aug. 7.
More than 1,000 firefighters were engaged in what fire officials called "a heavy air show" and ground assault in a drive to gain the upper hand over a blaze stoked by dry, hot weather and strong, gusting winds.
"Every fire has a personality, and this fire has an angry personality," said Beth Lund, incident commander with the U.S. Forest Service team managing the blaze in central Idaho.
Airplane tankers dumping payloads of fire retardant and helicopters dropping water bolstered the fight on Sunday to protect the 5,128 residences, 1,399 commercial properties and 3,729 outbuildings threatened by the fire.
For the first time since the so-called Beaver Creek blaze erupted, weather conditions on Sunday turned in favor of the firefighters.
A rise in humidity levels overnight paired with calmer winds gave crews an edge in efforts to subdue flames that have advanced on affluent neighborhoods around the tourist town of Hailey and resort communities of Ketchum and Sun Valley to the north.
Authorities have put the value of land and property threatened in the resort region, known as the Wood River Valley, at $8 billion. The area contains the homes of such celebrities as film director Steven Spielberg, actor Tom Hanks and singer and actress Barbra Streisand.
The 11-day battle against the flames has strained the economies of the resort towns at the height of a summer recreation season tied to hiking, biking and fishing.
At the Sun Valley Resort, an all-season vacation getaway famed for its world-class skiing, workers turned on water cannons usually used to make snow to wet down a mountain whose southeastern face was the scene of a concentrated assault by firefighters.
"We've fired up the snow-making guns," resort spokesman Jack Sibbach said of the computerized system.
On Sunday, fire managers expressed cautious optimism about their prospects for curtailing the blaze in the next week or so.
"I think we'll see this thing pretty well beaten into submission," Lund said. "It's kicked our butts for the last three days, but I think we're about to turn the corner on this one."
Word that firefighters were gaining ground on the fire was welcome news in Hailey, a city of 8,000.
"Saturday was really, really scary, but things seem to be looking up a bit today," said Carrie Morgridge, owner of Hailey Coffee Company.
Flames raced down a mountain on the west side of Hailey on Saturday, prompting a 3 a.m. evacuation of 200 homes. Morgridge opened the coffee shop during the pre-dawn hours to aid the displaced.
"In the good, in the bad, we will do what it takes to stay a community, to be an extended family, because that's really what we are," she said.
The Beaver Creek fire is one of dozens of blazes raging in western states amid a U.S. fire season that brought substantial property losses and the deaths of dozens of firefighters.
Elsewhere in Idaho, roughly 30 miles (48 km) to the west, the 1,000 summer residents of the resort communities of Pine and Featherville were allowed back into their homes early Sunday evening after a days-long evacuation prompted by a 130,000-acre (53,000-hectare) wildfire that broke out on Aug. 8.
The blaze east of the state capital Boise destroyed 38 homes and 43 other buildings and killed dozens of animals, including elk, deer and black bears. (Reporting by Laura Zuckerman; Editing by Steve Gorman and Paul Simao)