You couldn't pick a better time to visit. Daytime temps in the 50-65 F range. Night temps 30-40s. Be prepared for sub freezing. Bugs mostly gone.
I usually bring poncho tarp, 30F quilt, cookware, and fishing gear.
Merino baselayer and nylon pants to hike in.
Wind shirt if cold while hiking
Lightweight synthetic puffy for rest stops and camp.
It's a great time of year for minimalism.
Others may have different preferences, but it's a great time to be out, regardless.