I'll make a counterpoint as more than a few months makes it more likely to show up in Oregon in November or later, at which point likely hood of having wet conditions approaching Western Oregon significantly increases.
+1. I've crossed McKenzie Pass twice. Once in each direction. Mid September during Cycle Oregon. Both mornings it was quite chilly. The second time it was also wet on the west side. And Crater Lake in November? Good luck with that one. The north entrance and the rim road close with the first big snow, or on 10/1, whichever comes first.