If you have your tickets and other travel booked already, you should go on the trip - it's rather hard to know weeks ahead for any given day what conditions will be. The chances of terrible smoke every day during your trip are relatively low, given wind direction and general conditions right now, and the chance of less and less smoke in the Ashland area throughout August seems decent. There may even be a slight amount if rain in the next week or two.
Currently the worst fire in the region, called "Carr", is near Redding, CA; there are a number of other fires from Central Oregon down into Northern CA, including at least one in OR and two others in CA that are over 10k acres. However, most active fires near the CA-OR border are quite small right now. You will have to travel either through the Redding area on I-5, or take a route further from the fires (ie. closer to the coast, through Eureka) up US Hwys 101 and 1. You could avoid the smokiest areas if necessary given road conditions as they stand.
If you're willing to be flexible about the conditions in Ashland, and be willing to change the locations where you might stay in CA, things could work out perfectly fine. A few days indoors there wouldn't mean you couldn't still visit the coast, which is often immune to inland wildfire smoke. On the other hand, it is a small risk you're playing with, as it's looking like a bad fire season and new fires could be growing in Northern Calif by the time you get here.
If you're able to bring extra things with you in your suitcase that could help with adverse air conditions, that would be prudent. Extra clothing, water (bottles), and possibly masks are the most obvious. https://www.uline.com/Product/Detail/S-10479/Dust-Masks-and-Respirators/Uline-N95-Standard-Industrial-Respirator-with-Valve?pricode=WB0200
In short, it might seem like a good idea right now to cancel the trip due to what you see in the media, but if the weather clears up, you might really regret having spent the money! The main caveat is to watch changing conditions daily, including signing up for alerts from state & federal systems.
P.s. Useful information on fire conditions
For Calif: http://www.fire.ca.gov/general/firemaps
CalFire app and SMS alert: http://calfire.ca.gov/communications/socialmedia
For Mtn West: https://fsapps.nwcg.gov