SEATTLE — A cool, wet spring that drew out luxuriant growth in parts of the Pacific Northwest, followed by a ferociously hot and dry early summer, has created a fire-season tinderbox across the Pacific Northwest that exploded over the past week with dozens of wildfires burning hundreds of thousands of acres and forcing thousands of residents from their homes.
More than 3,500 people, including fire crews from all over the country and National Guard troops in Washington and Oregon, have been battling the fires. Spreading mostly across sparsely populated areas, the fires have a vast scope: Less than a week into the typical three-month fire season in Washington and Oregon, the total area of scorched ground is already higher than in any full year in at least a decade.
With the fire season elsewhere in the nation relatively quiet, the blazes in Oregon and Washington now account for a majority of the 33 large and uncontained wildfires being battled. The nearly 1,400 square miles — much of it grassland — burned in those two states accounts for more than two-thirds of the nation’s total wildfire losses since January.
The fires are having a stunningly visible impact in another way: A vast plume of smoke from them has drifted east and, along with smoke from a huge series of fires in the Northwest Territories of Canada, is spewing ash particulates across much of the U.S. from the Gulf of Mexico to New England, according to satellite imagery.
“The whole West is dry; they just happen to be at the ignition source,’’ said Jennifer Smith, spokeswoman for the National Interagency Fire Center in Boise, Idaho.
Fire officials said Monday that an interlude of cooler, damper weather, with the possibility even of some rain by midweek, had raised hopes that nature would intervene where human effort has in many cases been unsuccessful. The single largest fire, for example, in north central Washington — really a combination of three fires that merged, called the Carlton Complex — has burned about 380 square miles, and is only 2 percent contained.
The Carlton Complex has also damaged or destroyed about 150 structures, with one fatality attributed to it — a homeowner who had a heart attack while trying to protect his home. Thousands of residents have evacuated, with 1,200 families still out of their homes in 12 communities as of Monday morning, along a strip of mostly small agricultural towns on the eastern slope of the Cascade Mountains.
Washington’s commissioner of public lands, Peter J. Goldmark, said the cooler, damper weather was welcome, but the longer term forecast into next week is not so good, from a firefighter’s perspective. Much of the Northwest baked in a heat wave in early July, with temperatures over 100 degrees Fahrenheit in places and lower than normal humidity. The fires mostly flickered to life last Monday and Tuesday with lightning storms that were followed later in the week by winds of 30 mph or more that provided oxygen like a bellows.
“I think it would be presumptive to think that there isn’t more of the same coming,’’ Goldmark said, referring to the dry, hot weather pattern.
Some of the fires, in high elevation timber and National Forest lands, where few residents or communities are at risk, are being allowed to burn. The ones considered most dangerous — and where resources are being concentrated — are in the lower elevations where grass and timberlands merge.
The fires snake in a twisting pattern nearly 40 miles long by 27 wide. But in many places, witnesses and firefighters said, the landscape within the fire complex looks less like a traditional wildfire than a constellation of small and large blazes in every direction.
Another fire cluster, called the Chiwaukum Complex, was within about 9 miles of the tourist community of Leavenworth, where ash and smoke hung over the landscape.
Late Sunday, Gov. Jay Inslee of Washington amended an emergency declaration to include a ban on most outdoor and agricultural burning for 20 counties east of the crest of the Cascades, beginning immediately and continuing until at least noon on Friday.
“Weather conditions including high winds, lightning and high temperatures continue to make conditions extremely challenging,’’ Inslee said. “Our resources are stretched thin.’’
A spokesman for the Oregon Department of Forestry, Rod Nichols, said that with so many fires burning, fire becomes an inevitable hierarchy of risks, consequences and deployment. Oregon’s biggest fire, known as the Buzzard Complex, has burned more than 369,000 acres of mostly grassland in the state’s east central area, but much of the state’s valuable timberland has so far been spared, Nichols said.
“But with so many fires, it’s hard to single one out and say this is the bad one,’’ he said. “They’re all bad.’’