On Friday at 2:26 a.m. a dense fog advisory was released by the National Weather Service in effect until 10 a.m. for Tualatin Valley, West Hills and Chehalem Mountains, West Central Willamette Valley and East Central Willamette Valley.

"Visibility one quarter mile or less in dense fog," can be expected according to the weather service. "Fog will be the most prevalent in rural areas and along water bodies. Light winds through the morning may slow fog dissipation. There is a 30% chance that dense fog will remain through the early afternoon - especially within the Eola Hills and the Tualatin Valley."

News Source : https://www.oregonlive.com/weather-alerts/2025/12/dense-fog-advisory-for-oregon-until-friday-morning-visibility-as-low-as-1-4-mile.html