Autumn Equinox 2026: What You Expect From 23 September Now and What Changed Since the Greek Astronomer Hipparchus' Records?

The autumn equinox of 2026 arrives at 1.05am British Summer Time on Wednesday 23 September, which is why the calendars say the 23rd rather than the 22nd this year. In London the sun rises at 6.48am and sets at 6.56pm that day, giving 12 hours and 8 minutes of daylight, according to the Royal Observatory Greenwich. The day when light and dark are genuinely equal, the equilux, comes two days later, on the 25th.

The September event is an equinox, from the Latin for equal night. Solstices are the sun's turning points in June and December; equinoxes are the crossings in between, when the sun passes over the celestial equator and, for six months, the southern half of the world gets the better of the light.

What people want from that crossing has changed more than the crossing itself. Around 3000 BC, on a hilltop in County Meath, people built a stone chamber whose passage lines up with the equinox sunrise so that the first light travels the length of it and lands on a carved stone at the back. In 2026 that chamber is closed for conservation work. Stonehenge, which was never built for the equinox at all, will open free at dawn on the 23rd. And in between the two, the week is booked solid: a sound bath in a Chelsea garden, a twilight forest bathe among Anglo-Saxon burial mounds, mooncakes in Chinatown, a public holiday in Japan, and a candle range that reached Aldi's shelves on 13 August.