In 2025, fall is officially considered to begin on Monday, September 22, in the Northern Hemisphere, when the autumnal equinox occurs.

Quick Scoop: Which “official” fall?

There are actually two common answers people mean when they ask “when is it officially fall 2025?”:

  1. Astronomical fall (equinox) – the one most people mean.
    • Starts: Monday, September 22, 2025.
 * This is when day and night are nearly equal in length and the Sun crosses the celestial equator.
  1. Meteorological fall (for weather/climate folks)
    • Starts: Monday, September 1, 2025.
 * Meteorologists use fixed three‑month blocks: September–November for “fall.”

So if you’re asking “when is it officially fall 2025” in the usual calendar/space-nerd sense, the key date is:

September 22, 2025 – first day of fall (autumnal equinox) in the Northern Hemisphere.

If you tell me your country or city, I can also give the approximate local time of the equinox for your location.

TL;DR:

  • “Official” (astronomical) fall 2025: September 22, 2025.
  • Meteorological fall 2025: September 1, 2025.

Information gathered from public forums or data available on the internet and portrayed here.