The Carlton Complex blaze did not grow overnight, the first time since the fire was triggered by lightning strikes six days ago that it showed any sign of abatement, local officials said.
By early Sunday, the fire was still burning over 280,000 acres (113,311 hectares) in Washington's Methow Valley, about 120 miles (195 km) northeast of Seattle, but its perimeters were not expanding.
"It seems to be calming down a whole lot," said Okanogan County Sheriff Frank Rogers. "The weather is definitely a help. It's cooled down a whole lot. It's also burning out in some areas."
Ten people remained unaccounted for as of Sunday, though Rogers said that could reflect outages of phone service. No major injuries had been reported.
The blaze has scorched at least 336 square miles (870 sq km) of dry timber and grasslands in north-central Washington since Monday, destroying about 100 homes and forcing hundreds of people to evacuate in several towns and rural areas.
The wildfire was one of about 18 burning across the Pacific Northwest, from northern California to Idaho, amid drought-like conditions that have made the region's annual fire season more active than usual. The governors of Oregon and Washington each declared fire emergencies last week.
Washington Governor Jay Inslee was due Sunday to tour some of the affected areas, including the towns of Omak and Malott, which was under a second day of evacuation orders.
In the town of Pateros, home to about 650 people, some 40 homes and dwellings were destroyed and many others left badly damaged or uninhabitable, emergency management officials said.
Rogers said that if conditions continued to improve Sunday, some evacuation orders would be lifted across the region, home to about 10,000 people. Many area residents were likely to return to homes without electricity as a result of the fire knocking out power lines across the region.
The region's biggest fire, the lightning-sparked Buzzard Complex, has burned about 315,000 acres (127,476 hectares) in eastern Oregon and residents in the largely rural area on Sunday were experiencing heavy smoke conditions.
