I've fished this run a lot the last few years and found May to be the top month, though most fish come through March into June. Once the water temp gets above 60, forget it! That usually happens in June or July. Fishing can be good again in fall. Last year was excellent. I've not been out much this year. The one day I remember in April, I skunked and my partner caught a winter native.
We always did best in the fall.But then again, nobody fishes them in the fall so a few fish in the river make for a great day of fishing.
There is not a "peak" for summers, like winter fish that come in huge waves. They trickle in from Feb to November. May and June might be the best as far as numbers of fish go. But you can catch fresh fish for a long time. If the water is below 60 degrees, they will bite.
We drifted a good 15 miles yesterday on the upper river taking out at Carver (three of us) Had a couple bites and my buddy had one on for about 20 seconds. If you ask me its really really really slow right now. Talked to people fishing the mouth and got the same story. I guess the Temp. needs to drop in the Willamette for the Nooks to start running. I have to say though it was a beautiful day and beautiful river, catching fish is just the bonus. Zman