I did the Oregon Coast in Sept 2009 and had 1 day of rain, the rest of the time was great and I would say "do it now". I'm going to do Astoria to San Francisco
this Sept, might go all the way to San Diego if I have the time. I couldn`t do much touring last summer because of work and I really missed it, it`s one of the few things i do in life where i completely forget about everything else. I am going to get my fill this year.