Fall (also called autumn) has two common “start dates,” depending on how you define the season:

  • Meteorological fall starts on September 1 and runs through November 30 in the Northern Hemisphere.
  • Astronomical fall starts on the autumnal equinox , which usually falls on September 22 or 23 in the Northern Hemisphere, and on March 19–21 in the Southern Hemisphere.

For example, in 2026 in much of the Northern Hemisphere, astronomical fall begins around September 22–23, 2026 , when the Sun crosses the celestial equator and day and night are nearly equal.

People also talk about the “start of fall” more loosely—when weather cools down, leaves turn color, or seasonal drinks and decorations appear—so in everyday life you’ll often hear some say fall “starts” as early as late August or around Labor Day.