Call the Fall Foliage Hotline at 800-547-5445. Typically you would be looking at the first week in October but it can vary widely. I live in Portland and hope you get the chance to visit. There are many amazing opportunities.
You live in Portland? My experience with trying to shoot the famous tree there for fall colors is vastly different. I've never heard of that maple turning anywhere near the first part of October. It varies quite a bit, but it's more like late Oct/early november. I was there in Oct of 2013, showed up on the 25th, and was one day late. I still got a nice shot, but rain from the day before had knocked most of the leaves off of the famous Japanese Maple. It was prime for 2 or 3 days before that, so guessing the 21-24th. So the next year I headed down a few days earlier, and the tree had barely started to change ... it didn't peak until into November. Friend of mine went that same year in early november and got some nice shots of the tree.
Going to try it again this year, but my plan is to be very flexible and head there after I know the tree is changing and spend enough time to hit the Japanese Gardens a couple of times with a several day interval between, somewhere between Oct 22 and November 3 or 4th.
I don't know if those up the canyons and through the gorge get amazing with colors, because I think some stay green year round? But there are definitely some yellows intermingled. attached 3 shots, first is the maple on 10/25/13, second is the maple on 10/21/2014 (and it didn't peak until Nov that year). Third is Metlako Falls also on the 10/21/2014. I assume there would have been more yellows closer to when the maple also peaked in early Nov. that year.
