July and August are usually great summer weather - though I never had to deal with forest fire smoke when I lived there. Often June is nice as well.

These are the Seattle Tourism marketing months. Microsoft's college interns got the best weather of the year.

What they don't tell prospective residents is that the other 9 or 10 months of the year will be gray and drizzly/rainy, esp. December to March.

I could deal with the inclement weather, but one person I knew had to get a bright light to treat his seasonal affective disorder.