Autumn equinox 2026: When is it and what happens?

Image source, Getty Images By Elizabeth Rizzini Lead Weather Presenter Published 20 September 2026 Updated 24 minutes ago Astronomical autumn begins this week, with the autumn equinox taking place in the early hours of Wednesday.

The equinox will occur at 01:06 BST on 23 September, according to Royal Museums Greenwich.

It is a precise moment in time when the Sun crosses the celestial equator and neither hemisphere is tilted towards or away from the Sun, meaning day and night are roughly equal in length across the world.

And while the equinox itself cannot be seen, the day has cultural and spiritual significance for some people. Gatherings take place at sites including Stonehenge, where people come together to mark the occasion and watch the Sun rise.

Image source, Getty Images Image caption, Many people, including druids and pagans, gather at Stonehenge to take part in a autumn equinox celebration