The South Willamette Valley has been blanketed in fog and clouds with an air stagnation advisory in place for more than a week.
At the Oregon Coast Monday, the sun was shining and the temperature was in the mid-50s. Meanwhile Eugene-Springfield has been encased in fog and clouds with temperatures barely edging above 40.
Colby Newman is a meteorologist with the National Weather Service in Portland. He says it's all because of a high pressure system over the west coast.
Newman: "That allows the fog to just stay there and it just does not mix out and if it were summertime the sun would be strong enough that that air would sort of help rise high enough to get up over the coast range and over the cascades and sort of allow that fog to burn off and go elsewhere."
Newman says on Thursday wind is expected to pick up in the region. It may help transport the fog and stagnant air out of the South Willamette Valley. The Lane Regional Air Protection Agency says air quality in Eugene / Springfield is good. In Oakridge, it is unhealthy for sensitive groups.