I use the Swell Watch website for most of my forecasts. I look for swell conditions in which the heigh in feet is at least 3 larger than the swell period in seconds. I also want winds of <=15kts. This rule works for for swells up to about 5' after which I want a period greater that is 4-5 larger. In late July through early Sept. I would say that 60-80% of the days meet this criteria (especially in August). I look for times when Swell Watch has predicted 2-3 good days in a row and plan my trips to hit the center of their predictions. So far that has worked quite well and I haven't been too surprised by anything (other than the wind coming up a bit one night when I was overnighting offshore).