By Jim Christie

SAN FRANCISCO, July 8 (Reuters) - Wildfires raged on Sunday across the western United States as firefighters scrambled to prevent flames from spreading across rugged terrain thick with tinder turned bone-dry by scorching hot weather.

Some of the intense blazes forced hasty evacuations of rural homes and recreational areas and officials temporarily shut highways and railways in some fire zones.

California, Arizona, Nevada, Utah, New Mexico, Oregon, Washington, Idaho and Montana each reported wildfires of varying severity amid a heat wave blanketing the western United States.

Fanned by high winds, a fire in Utah had grown into a massive blaze of more than 160,000 acres (65,000 hectares) and in neighboring Nevada a fire burning 30 miles (48 km) southwest of the town of Winnemucca had consumed an estimated 152,000 acres (62,000 ha). The two fires forced temporary closures of major interstate highways.

Neighborhoods in Winnemucca were temporarily evacuated on Saturday as a separate fire that had burned an estimated 25,000 acres (10,000 ha) of brush neared.

"People are back in their homes now but we're keeping a very close eye on this fire," Jamie Thompson, a spokesman for the U.S. Bureau of Land Management, told Reuters in a telephone interview. "There is a potential for extreme fire conditions today as well."

Lightning on Friday triggered both blazes near Winnemucca and fire crews are on alert for more strikes.

"Isolated cells were moving through the area. They had very little moisture but plenty of lightning," Thompson said.

"There is still the potential for isolated thunder storms with lightning of course this afternoon," he added.

In California, lightning-sparked fires in the Inyo National Forest forced the evacuations of numerous campgrounds. The blazes had scorched an estimated 34,000 acres (14,000 ha) since breaking out on Friday, according to the U.S. Forest Service.

The Forest Service had imposed fire restrictions a week earlier in all Inyo National Forest lands and neighboring Bureau of Land Management lands, expecting increased fire danger from hot, dry weather.

Fire officials across the western United States have been bracing for a busy fire season after scant rainfall this past winter.

AlertNet news is provided by