Pack with layers, none of them cotton. I usually have a breathable rain jacket or parka along for the top layer to combat wind, rain or snow. You may be down to a tee shirt in the afternoon and back up to 3 or 4 layers by evening.

September is a great month for Western trout fishing. Water temperatures are good for the fish. Terrestrials still work. The trout are instinctively chowing down hard in anticipation of the coming winter. Hope you have a greet trip!