The first day of fall (astronomical autumn) in 2026 is Wednesday, September 23 in the Northern Hemisphere.

Here’s the quick scoop:

  • Astronomical fall 2026 : Starts at the autumnal equinox, which occurs at 00:05 UTC on September 23, 2026 (that’s the moment the sun crosses the celestial equator heading south).
  • Meteorological fall : Many weather and climate agencies define fall more simply as September 1 to November 30 every year, regardless of the equinox.

Why the date moves a little

The equinox doesn’t fall on the exact same calendar date every year; it usually lands between September 21 and 24 because of the way our calendar fits around Earth’s orbit and leap years. In 2026, this wobble puts the equinox—and thus the official first day of fall—on September 23.

How people talk about “when fall starts”

In everyday life, people often say “fall starts” when:

  • The calendar flips to September (meteorological definition).
  • The weather finally turns cooler, leaves change, and it feels like fall—often late September or even October in warmer places.

But if you’re asking in the strict, official sense for 2026, the first day of fall is Wednesday, September 23. Information gathered from public forums or data available on the internet and portrayed here.