A few weak weather systems will graze by Southern Oregon the next several days. This will bring a mix of clouds and sunshine, but not a lot of wind to mix the valleys of the inversions. The result will be a build-up of pollution (especially the Particular Matter or PM).
Otherwise, some valley fog and low clouds will be possible at night and in the morning hours through Friday. Clouds above the fog will come and go, with a layer of thicker clouds Wednesday and Thursday, followed by sunny skies Friday…ahead of a cold front that we think will be strong enough to stir up the valley inversions. A stronger front will arrive on Monday.