September equinox 2025


When is the September equinox 2025?

The September equinox 2025 is on Monday, September 22, 2025 (in 96 days).  Calendar for 2025
Please note: The dates given on this page are based on Coordinated Universal Time (UTC), which for practical purposes is equivalent to Greenwich Mean Time (GMT). While the September equinox occurs at the same moment in time all over the world, the date and local time differ from location to location depending on a location's time zone. For more details see the explanations below.
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What is the September equinox?

The September equinox marks the beginning of autumn in the Northern Hemisphere. Photo: flickr.com/photos/infomastern/15151599616The September equinox marks the beginning of autumn in the Northern Hemisphere
The September equinox, also called southward equinox, is the moment in time (not a day-long event) when the Sun stands directly above the equator while crossing from the north to the south. For the Northern Hemisphere (where nearly 90% of the world's population live) it is the autumn equinox (fall equinox) as it is the moment when summer ends and autumn (fall) begins, while for the Southern Hemisphere it is the vernal equinox (spring equinox), the moment when winter ends and spring begins. Up until the September equinox the Sun rises and sets more to the north of the equator, and afterwards it rises and sets more to the south.

The September equinox usually occurs every year between September 21 and 24. The dates given on this page are based on Coordinated Universal Time (UTC), which for practical purposes is equivalent to Greenwich Mean Time (GMT - the time zone of the United Kingdom). While the September equinox occurs at the same moment in time all over the world, the date and local time differ from place to place depending on the year and a location's time zone. For locations that are ahead of UTC (further east) it may fall on the day after, and for locations that are behind UTC (further west) it may fall on the day before. To find out the exact date and time of the September equinox 2025 in your area use this seasons calculator.

The September equinox is one of four days with solar events (two equinoxes and two solstices) throughout the year that mark the beginning of a new season. The other days are the March equinox, the June solstice and the December solstice.

The word "equinox" is derived from Latin and means "equal night". On the day of an equinox, day and night are of approximately equal length all over the world, as the Earth's rotational axis is neither tilted away from nor towards the Sun. At all other times the length of day and night will be different.


The exact moment of the September equinox through the centuries
The exact moment of the autumn equinox between 1900 and 2520. Originally by Frank Klemm, de.wikipedia.org/wiki/Datei:Herbstanfang.png, Creative Commons, CC-by-sa 3.0/de
Graph demonstrating the movement (caused by leap shifting) of the exact moment of the September equinox between 1900 and 2520. X axis (bottom, horizontal): Calendar years, Y axis (left, vertical): day in September (21 to 23).

In a non-leap year, the moment of the September equinox is about 5 hours 49 minutes after that moment in the previous year (in UTC), and in a leap year it is about 18 hours 11 minutes before that moment in the previous year, as can be seen in this graph. In this way the time of the September equinox constantly shifts back and forth so it always stays between September 21 and 24. This four year cycle is clearly visible in the graph.

To adjust for the gradual movement backwards on the calendar (as visible for the period 1900 to 2099), in years divisible by 100 (1900, 2100, 2200, 2300 and 2500 on the graph), which should be leap years as they are divisible by 4, the leap day is omitted (except when they are divisible by 400, eg. 2000 and 2400) and the moment of the September equinox moves forward in time compared to the same moment in the year before.

Further reading:

Overview: seasons, equinoxes and solstices

Dates shown apply to the Northern Hemisphere and are based on UTC (GMT)
Season Start End
Spring Spring equinox
(vernal equinox, March equinox)
March 19 to 21
Summer solstice
(June solstice)
June 20 to 22
Summer Summer solstice
(June solstice)
June 20 to 22
Autumn equinox
(Fall equinox, September equinox)
September 21 to 24
Autumn
(Fall)
Autumn equinox
(Fall equinox, September equinox)
September 21 to 24
Winter solstice
(December solstice)
December 20 to 23
Winter Winter solstice
(December solstice)
December 20 to 23
Spring equinox
(vernal equinox, March equinox)
March 19 to 21

When is the September equinox 2026?

The September equinox 2026 is on Wednesday, September 23, 2026 (in 462 days).  Calendar for 2026

Dates for the September equinox in other years

The next occurrence of the September equinox is marked in red.

When is ...? Date      Day of the week      Days away     
September equinox 2020      September 22, 2020      Tuesday      1730 days ago
September equinox 2021      September 22, 2021      Wednesday      1365 days ago
September equinox 2022      September 23, 2022      Friday      999 days ago
September equinox 2023      September 23, 2023      Saturday      634 days ago
September equinox 2024      September 22, 2024      Sunday      269 days ago
September equinox 2025      September 22, 2025      Monday      in 96 days
September equinox 2026      September 23, 2026      Wednesday      in 462 days
September equinox 2027      September 23, 2027      Thursday      in 827 days
September equinox 2028      September 22, 2028      Friday      in 1192 days
September equinox 2029      September 22, 2029      Saturday      in 1557 days
September equinox 2030      September 22, 2030      Sunday      in 1922 days
Data provided 'as is' without warranty

September equinox 2025
Dates of the September equinox 2025 and surrounding years as downloadable image file

Printable 2025 Calendars for PDF, Excel and Word


Calendar templates 2025 for PDF, Excel and Word

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