Offshore winds expected to drive Northwest wildfire smoke into Seattle and Portland
Changing wind patterns will push smoke from eastern Oregon and Washington fires into western Washington and Oregon, raising air-quality concerns for the Seattle-Portland corridor through midweek.
Ground-level smoke from a series of large wildfires burning in eastern Oregon and Washington is forecast to move westward as offshore winds develop over the next few days. The shift from the usual east-to-west onshore flow to winds from the east or northeast will carry particulate haze into western Washington and Oregon, affecting the Interstate 5 corridor, including Seattle, Tacoma, Olympia, Portland, Salem, Corvallis and Eugene. Models also suggest the smoke could reach as far south as Salt Lake City.
The smoke plume is expected to linger at least until Wednesday, while daytime temperatures may rise toward 90 °F in Seattle and approach the upper 90s in Portland, though dense smoke could modestly lower peak temperatures. A gradual cooling trend is projected for the weekend, and monsoon-related thunderstorms may affect the northern Rockies next week, bringing both potential rain and the risk of flash flooding in recently burned areas.
Health officials advise monitoring local air-quality indexes, which range from green (good) to maroon (hazardous). When the index reaches orange, people with respiratory or heart conditions, the elderly, children and pregnant individuals should limit outdoor exposure. At red, purple or maroon levels, everyone is urged to stay indoors as much as possible and keep outdoor activities brief.
The particulate matter in wildfire smoke can irritate the lungs and enter the bloodstream, causing short-term symptoms such as coughing, shortness of breath, sore throat, runny nose and eye irritation, and may increase the risk of chronic lung disease, heart attacks and strokes with prolonged exposure.