Almanac · Seasons

September equinox 2026

The September equinox was on Wed 23 Sep 2026 at 00:05 UTC: the instant the Sun crossed the sky’s equator heading south, overhead at noon at the equator. It begins astronomical autumn in the northern hemisphere and spring in the southern. The next is the September equinox 2027.

• Equinox Wed 23 Sep 2026, 00:05 UTC
• Sun overhead at noon The equator The Sun’s declination then: +0.00°
• Daylight 12 h 11 min at 45°S 12 h 06 min at 15°N

The day at each latitude

Sunrise and sunset on Wed 23 Sep 2026 at each latitude, how long the Sun is up, which way to face to see it rise and set, and how high it climbs at noon. Times are local solar time: your clock may differ by up to an hour or two, by your time zone.

How we worked it out: the equinox is the instant the Sun’s apparent longitude reaches 180°, found to the second from the Earth’s place in VSOP87, carried to the equinox of date and given nutation and aberration, as Meeus works these instants out; the tests hold it to the U.S. Naval Observatory’s time within the minute. Sunrise and sunset are the Sun’s upper edge on a level horizon, with refraction, as /tonight gives them, at Greenwich’s longitude, and the bearings are measured from due east and due west.

• J. Meeus, Astronomical Algorithms, ch. 27: the instants of the equinoxes and solstices, from the Sun’s apparent longitude
• P. Bretagnon and G. Francou, VSOP87: the Earth’s place, which the Sun’s is the reverse of, as the planets are seen from it
• U.S. Naval Observatory, Earth’s Seasons: the instants the tests hold these to, within the minute
• J. Meeus, Astronomical Algorithms, ch. 15 and 25: sunrise and sunset, as /tonight gives them

All equinoxes and solstices · September equinox 2025 · September equinox 2027 · Why we have seasons · The year’s sky almanac · Tonight