Temps will be mostly highs in the 60s, lows in the 40s, but there will be an occassional cold front move through. Maybe a few warm days as well.

Check out the seasonal hstory for PCB here:
Average High/Low Temperatures for KPFN : Weather Underground

And, bring mostly casual clothes. Pretty much everything in PCB is casual. Although you might want to bring something for Boatyard's Little Black Dress event.