Autumnal equinox 2021


When is the Autumnal equinox 2021?

The Autumnal equinox 2021 is on Wednesday, September 22, 2021 (in 336 days).  Calendar for 2021
The Autumnal equinox 2020 has already passed: it was on Tuesday, September 22, 2020 (29 days ago).  Calendar for 2020
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 Autumnal 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.

What is the Autumnal equinox?

The autumnal equinox marks the beginning of autumn. Photo: flickr.com/photos/flatworldsedge/5140846204The autumnal equinox marks the beginning of autumn in the Northern Hemisphere
In the Northern Hemisphere, the moment in time when the Sun stands directly above the equator while crossing from the north to the south is called autumnal equinox (also known as fall equinox, September equinox or southward equinox). It is the moment summer ends and autumn (fall) begins in the Northern Hemisphere (where nearly 90% of the world's population live). For the Southern Hemisphere, it is the vernal equinox (also called spring equinox) as it is the moment winter ends and spring begins.

In the Northern Hemisphere the autumnal equinox 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 autumnal 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 autumnal equinox 2021 in your area use this seasons calculator.

The autumnal equinox is one of four days (two equinoxes and two solstices) throughout the year that mark the beginning of a new season. The other days are the vernal equinox (beginning of spring), the summer solstice (beginning of summer) and the winter solstice (beginning of winter).

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 autumnal equinox through the centuries
The exact moment of the autumnal 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 autumnal 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 autumnal 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 autumnal 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 autumnal equinox moves forward in time compared to the same moment in the year before.

Further reading:
September equinox on Wikipedia
Equinoxes in general on Wikipedia

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 Autumnal equinox 2022?

The Autumnal equinox 2022 is on Friday, September 23, 2022 (in 702 days).  Calendar for 2022

Dates for the Autumnal equinox from 2016 to 2026

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

When is ...? Date      Day of the week      Days away     
Autumnal equinox 2016      September 22, 2016      Thursday      1490 days ago
Autumnal equinox 2017      September 22, 2017      Friday      1125 days ago
Autumnal equinox 2018      September 23, 2018      Sunday      759 days ago
Autumnal equinox 2019      September 23, 2019      Monday      394 days ago
Autumnal equinox 2020      September 22, 2020      Tuesday      29 days ago
Autumnal equinox 2021      September 22, 2021      Wednesday      in 336 days
Autumnal equinox 2022      September 23, 2022      Friday      in 702 days
Autumnal equinox 2023      September 23, 2023      Saturday      in 1067 days
Autumnal equinox 2024      September 22, 2024      Sunday      in 1432 days
Autumnal equinox 2025      September 22, 2025      Monday      in 1797 days
Autumnal equinox 2026      September 23, 2026      Wednesday      in 2163 days
Data provided 'as is' without warranty

Autumnal equinox 2021 Dates of the Autumnal equinox 2021 and surrounding years
as downloadable image file




Printable 2021 Calendars


Calendar templates 2021 for Word, Excel & PDF
Calendar templates 2021 for Word, Excel & PDF

2021 calendar as templates for
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A selection of calendar templates for 2021 in landscape and portrait orientation and with US federal holidays, suitable for a variety of applications.

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Vernal equinox (spring equinox,
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September equinox)
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