Key Facts

• The autumn equinox happens when the Sun crosses the celestial equator, occurring on 23 September 2026 at 01:06 BST.
• On the equinox, day and night are about the same length all over the world.
• The equilux, the day when daylight and darkness are exactly equal, occurs a few days after the equinox, around 25 or 26 September in the UK.
• Light refraction by the atmosphere makes daylight slightly longer than 12 hours at the equinox.
• People celebrate the equinox at places like Stonehenge, where they watch the sunrise.
• Northern parts of the UK lose daylight faster than southern parts as autumn progresses.
• The equinox signals the start of astronomical autumn but does not directly cause immediate colder weather.
• This September, UK temperatures have been higher than average, with slightly warmer and changeable weather expected through the end of the month.