Dense Smoke Advisory issued September 06 at 12:08AM PDT until September 07 at 12:00PM PDT by NWS

...Dense smoke expected through midday Thursday... .Periods of dense smoke will persist through midday Thursday across the mid-elevations and valleys of Siskiyou County from the Shasta Valley westward. Dense smoke will also persist in the Southern Oregon Cascades near Union Creek and Diamond lake and in eastern Douglas county near Steamboat through late this evening.

from Current Watches, Warnings and Advisories for the United States Issued by the National Weather Service http://ift.tt/2j11BIO