On Friday at 7:38 a.m. a dense fog advisory was issued by the National Weather Service in effect until noon for West Central Willamette Valley, East Central Willamette Valley, Benton County Lowlands and Linn County Lowlands.

"Light winds and limited air movement will lead to a period of stagnant air conditions," NWS said, warning of "deteriorating air quality for people with respiratory problems" and "visibility one quarter mile or less in dense fog," which "could make driving conditions hazardous."

On Sunday at 2:52 a.m. the NWS Hanford CA issued a dense fog advisory valid for Sunday between 4 a.m. and 10 a.m. The advisory is for Merced - Madera - Mendota, West Side of Fresno and Kings counties,

An updated dense fog advisory was issued by the National Weather Service on Thursday at 11:49 a.m. in effect until noon for Central Douglas County.