Late November often brings persistent valley fog to Pacific Northwest lowlands, with dense mist settling into the Willamette Valley, Puget Sound basin, and other inland areas for days at a time. These fog events occur when high pressure builds aloft while cold, moist air remains trapped in valleys below, creating stubborn inversions that resist daytime heating. The fog can be so dense that visibility drops below a quarter mile, and it may persist continuously for 3-7 days without clearing. During these events, valley temperatures remain in the mid-30s to low-40s, while nearby mountain locations above the fog layer enjoy sunshine and temperatures 20-30 degrees warmer. The eerie, gray landscapes and shortened days (less than 9 hours of daylight by late November) create a distinctly somber atmosphere that tests even dedicated Pacific Northwesterners. These fog events typically break when stronger storm systems move through.

Hazelnuts from Oregon's Willamette Valley reach harvest peak, adding distinctive Northwest flavor to holiday baking. Cranberries from Oregon's South Coast, wild mushrooms (chanterelles, hedgehogs), and storage crops (potatoes, winter squash) dominate Thanksgiving tables alongside Dungeness crab season's sweet harvest.

Watch for bald eagles beginning to gather at salmon spawning rivers—Skagit River, Nooksack River, and Fraser Valley see early arrivals following chum salmon runs, though peak eagle viewing comes later in December and January. Plan eagle-watching trips for the coming weeks as thousands will congregate at these sites.