September Equinox Date. The spring equinox, which similarly marks the start of the season,. Utc) on september 22, officially marking the beginning of fall in the northern hemisphere and the start of spring in the southern.

In 2019 september 23 is the date of the september equinox and is also the first day of autumn (or the first day of spring if you’re one of my readers in the southern. For the northern hemisphere, it means the summer is over, but in the southern latitudes, the spring just begins.