Yesterday was Labor Day. I'm guessing you feel that now it's past, autumn begins. I have that sense even though I know autumn technically doesn't start until the 21st of the month.
Part of why I feel autumn has arrived is that, at 6300 ft., autumn begins early. Summer here is nearly perfect, but like most wonderful happenings, it's entirely too short.
Summer starts late and ends early. We don't need air conditioning but the sweet spot truly lasts maybe two months tops, maybe a bit less. Late spring and early fall here aren't bad, but they're not summer.
Whatever ... it was great while it lasted.