On Monday at 9:56 a.m. an air stagnation advisory was issued by the National Weather Service valid from Tuesday 4 a.m. until Friday 4 p.m. for Lower Columbia River, East Central Willamette Valley, Benton County Lowlands, Linn County Lowlands, Lane County Lowlands, Clackamas County Cascade Foothills, Cascade Foothills of Marion and Linn counties and Lane County Cascade Foothills.

The weather service says to be ready for, "Light winds and limited air movement will lead to a period of stagnant air conditions."

News Source : https://www.oregonlive.com/weather-alerts/2026/02/air-stagnation-advisory-active-for-willamette-valley-from-tuesday-to-friday.html