Cool, humid weather Sunday helped slow the advance of a fire that caused the evacuation of hundreds of homes and businesses in Alaska's Interior, and forecasters predicted wetter weather would soon follow.

The evacuation order remained in effect as the fire spread over 306,000 acres, up from 280,000 the day before.

Susan Woods was among the few evacuees allowed to return home as much of the heavy smoke blanketing the region about 30 miles north of Fairbanks dissipated.

"To get in my own bed seems more appealing than celebrating the Fourth of July," she said before leaving the truck-stop lot that had been her temporary home for five days.

Many residents camped out at the truck stop with their pets. Others took their animals, including horses, llamas, reindeer and goats, to the fairgrounds in Fairbanks.

Firefighters planned to bulldoze and burn out a fire line between evacuated areas and the southwestern edge of the fire, which has damaged at least one home, fire information officer C.J. Norvell said.

The Alaska Army National Guard dispatched two helicopters equipped with 900-gallon buckets that can be used to drop water on fires.

The fire, started June 13 by lightning, is considered 15 percent contained, fire officials said. It was the largest of 62 fires active in the state Sunday, and the only one with an evacuation order in effect. So far this year, more than 1.8 million acres in Alaska have burned.

In Arizona, a 4,090-acre fire about 110 miles northeast of Tucson threatened the observatory that is home to the $120 million Large Binocular Telescope, one of the world's most powerful optical instruments.

Firefighters planned to build a protection line around Mount Graham International Observatory and reinforce nearby roads that will be used as barriers against the blaze.

The fire, which was caused by lightning, and a 5,254-acre fire nearby prompted the evacuation of the observatory and 70 to 80 houses on the mountain Friday. No houses or cabins were imminently threatened, but state officials issued a health advisory to protect people in nearby towns from smoke.