Firefighting teams across the West Coast faced unpredictable wind gusts and drier weather Monday, conditions that threatened to make new kindling out of forests and strengthen already dire wildfires that have burned more than 5 million acres, destroyed scores of homes and left dozens of people dead.

Disastrous wildfires this season have forced hundreds of thousands of people out of their homes and turned forests, fields and communities into blasted landscapes, covered by hazardous smoke and falling ash.

State leaders have raced for weeks to contain one spiraling fire after another, straining their emergency services and prompting them to plead for help from other states and the federal government.

Authorities have warned for days not to expect relief soon, saying that even though winds could help disperse some of the smoke that has smothered cities like San Francisco and Oakland, California, it could also dry out brush and fan flames, reversing the progress firefighters have made. The winds, caused by a slow-moving storm system off the coast of Oregon, were expected to last most of the week and could push smoke to Montana, Idaho and even Canada, meteorologists said.

“Fundamentally, the science is very, very simple,” said Philip Duffy, a climate scientist who is president of the Woodwell Climate Research Center. “Warmer and drier conditions create drier fuel,” he said. “What would have been a fire easily extinguished now just grows very quickly and becomes out of control.”

The season has already felt out of control to many officials, as fires have destroyed towns and approached dense suburbs. The town of Paradise, California, where more than 80 people died two years ago, is now on the edge of a fire to its east, the North Complex Fire, that is one of the largest in the state. To its west is California’s largest: a group of fires called the August Complex that has burned nearly 1 million acres.

Some of the worst conditions remained in Oregon, however, where more than 30 active fires have burned 900,000 acres. The Beachie Creek fire, a blaze south of Portland that has destroyed almost 200,000 acres and killed four people, continued to burn uncontrolled Monday.

Though the relative humidity remained low early Monday, there was hope more moisture would be carried into the region later.

“We want a lot of moisture in the air,” said Michelle Mead, a National Weather Service meteorologist in Sacramento. “And we don’t have that right now.”

Most of what has burned in the West has been in remote forests, but in Oregon, entire communities along Interstate 5, the main north-south highway along the West Coast, have been razed.

“We haven’t had anything ever this close,” said Margot Cooper, who for the last three decades has lived in Scio, Oregon, a farming and logging town southeast of the state capital, Salem. “It’s the first time it’s literally in our backyard.”

Last week a 13-year-old boy was killed in a nearby canyon.

In nearby Gates, evacuees from the fires were exhausted after five days of living in motels or cars, eating donated pizzas for dinner and, all the while, not knowing whether their homes had burned down or were standing.

Police cruisers blocked traffic along a highway heading into the mountains east of Salem, where the Beachie Creek Fire was still burning out of control. Some families were able to pass through. Other convoys of pickup trucks threaded their way onto side roads and skimmed the edges of farm fields in search of alternate routes. Some were seeking needed medications, others lost pets, and there were signs of break-ins and looting.

“Everything’s still on fire,” said Mike Alexander, 29, who has been coming and going since the night of Sept. 7, when the wildfire surged up the hillside behind his home.

Meanwhile, a man in Oregon has been arrested twice in less than 12 hours after he was accused of starting more than a half-dozen small fires along a freeway, police said Monday. None of the fires caused injuries or damage to structures.

The suspect, Domingo Lopez Jr., 45, was first spotted Sunday afternoon when a brush fire was lit along Interstate 205, a north-south freeway that runs east of the Portland metropolitan area, the Portland Police Bureau said. He was booked into the Multnomah County Detention Center on charges of reckless burning and disorderly conduct, police said.

He was released on his own recognizance, inmate records show. A little after 3:30 a.m. Monday, Lopez was arrested a second time while walking on the side of a road, with police saying he had started six more small fires along the freeway.

Lopez was given citations for six more counts of reckless burning and taken to the hospital for a mental health exam, police said.