It’s just the September Equinox
The September equinox arrives on September 23 at 8:21 UTC. Although the equinox happens at the same moment worldwide, the clock times vary by time zone.
In the Northern Hemisphere, the sun is rising later now, and nightfall comes sooner. This is our autumn equinox, when the days are getting shorter in the Northern Hemisphere. At this equinox, day and night are approximately equal in length. For us in the Northern Hemisphere, people are enjoying the cooler days of autumn even as preparations for winter are underway.