What Autumn Equinox is

The moment the sun crosses the celestial equator heading south, when day and night are near equal and the northern hemisphere tips towards winter.

It is the start of astronomical autumn in the north and spring in the south.

When it falls, and why the date moves

The countdown at the top of this page is live, and the date beneath it is the next occurrence. This is a fixed date: it falls on the same day of the month every year, so only the weekday changes.

It is grouped here under Astronomy, alongside the other observances that share its calendar.

What is coming up next

Once this date passes, the countdown moves straight on to the next occurrence — you do not need a different page for next year. See the full list of upcoming events, or use the countdown timer for a date of your own.

Where to go next

This autumn equinox countdown has its own page, so the link keeps working next year as well as this one. If you came here wondering what time it is somewhere rather than how long is left, World Clock has the current time in every country and city.

• event countdowns — live countdowns to holidays and festivals worldwide
• countdown timer — count down from any length you set
• World Clock — pick a country or city and read its clock, offset and daylight saving rules
• time zone converter — turn a time in one place into the same instant in another
• local time in every country — the current time in every country, territory and US state