With historically short summers, the swath of densely forested coastal territory stretching from British Columbia into northwestern Oregon has long been cloaked in a protective veil of moisture, making even medium-sized fires relatively rare. So-called “megafires” — enveloping hundreds of thousands of acres and even generating their own weather — have occurred only at century-plus intervals.
But global warming is changing the region’s seasons. A national climate assessment prepared by 13 federal agencies and released in 2018 said the Pacific Northwest had warmed nearly 2 degrees Fahrenheit since 1900 and that trend would continue into the century, leading to warmer winters and less mountain snowpack.
Experts say these long-term changes create a special risk in Pacific Northwest forests, where past wet weather has created ample fuel for fires: Even a modest increase in contributing factors, like days without rain, could make them much more prone to burning.