Fall Equinox Day 2025. The september equinox occurs at 18:17 utc. This is also the first day of fall (autumnal equinox) in the northern hemisphere and the first day of spring (vernal equinox) in the southern.
The first day of fall in 2025, also known as the autumnal equinox, will be on september 23rd. The sun will shine directly on the equator and there will be nearly equal amounts of day and night throughout the world.