What Is The First Day Of Fall 2024 Usa. Noaa’s climate prediction center says much of the u.s. The first day of autumn often called fall (september equinox or autumnal equinox) is when the sun shines directly on the celestial equator passing from north to.

The autumnal equinox is an astronomical event that marks the start of autumn. Noaa’s climate prediction center says much of the u.s.