Autumn Equinox 2017 in Northern Hemisphere will be at 3:02 PM (CDT) on Friday, September 22.
It is the summer’s great last heat,
It is the fall’s first chill: They meet.
–Sarah Morgan Bryan Piatt
WHAT IS THE AUTUMNAL EQUINOX? by the Old Farmer’s Almanac
The Autumnal equinox—also called the September equinox—is the astronomical start of fall in the Northern Hemisphere and spring in the Southern Hemisphere.