Here in the high country we generally consider Labor Day to be the end of summer and the beginning of autumn. Autumn arrives early, just as summer arrives late because of the altitude, locally 6000+ feet.
Another way of saying the same thing is we have short summers and long winters. Sadly true, but the trade off is that summers are pleasant and almost never sweltering. Late spring and early autumn are usually pleasant too, so it “works” for us snowbirds.
We haven’t seen much in the way of fall foliage yet. Our aspens and cottonwoods are still green and the mountain maples haven’t begun to go crimson. They’ll all show up in the next month and we get a beautiful week or two that rivals New England.
Locals who’ve found ways to enjoy winter like it here all year. Quite a few have snowmobiles and many hunt elk for the freezer. A fair few ski, we're told most go to Grand Targhee on the Idaho side of the Tetons as it is more affordable than the slopes of Jackson Hole. Retired locals, however, often winter somewhere warm, or wish they could.