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September

Ninth month in the Gregorian and Julian calendars

Wikipedia contributorsAdapted for Fathomly · View authors
12 min read
Source updated September 10, 2026
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September is the ninth month of the year in the Julian and Gregorian calendars. Its length is 30 days.

September in the Northern Hemisphere and March in the Southern Hemisphere are seasonally equivalent. In the Northern Hemisphere, the beginning of the meteorological autumn is on 1 September. In the Southern Hemisphere, the beginning of the meteorological spring is on 1 September.

September marks the beginning of the ecclesiastical year in the Eastern Orthodox Church. It is the start of the academic year in many countries of the northern hemisphere, in which children go back to school after the summer break, sometimes on the first day of the month. Some Libras and Virgos are born in September, with Virgos being born on September 1st through September 22nd and Libras September 23rd through September 30.

September (from Latin septem, "seven") was originally the seventh month in the oldest known Roman calendar, the calendar of Romulus c. 750 BC, with March (Latin Martius) being the first month of the year until perhaps as late as 451 BC. After the calendar reform that added January and February to the beginning of the year, September became the ninth month but retained its name. It had 29 days until the Julian reform, which added a day.

01Events

Ancient Roman observances for September include Ludi Romani, originally celebrated from September 12 to September 14, later extended to September 5 to September 19. In the 1st century BC, an extra day was added in honor of the deified Julius Caesar on 4 September. Epulum Jovis was held on September 13. Ludi Triumphales was held from September 18-22. The Septimontium was celebrated in September, and on December 11 on later calendars. These dates do not correspond to the modern Gregorian calendar.

September was called the "harvest month" in Charlemagne's calendar. September corresponds partly to the Fructidor and partly to the Vendémiaire of the first French republic. September is called Herbstmonat, harvest month, in Switzerland. The Anglo-Saxons called the month Gerstmonath, barley month, that crop being then usually harvested.

In 1752, the British Empire adopted the Gregorian calendar. In the British Empire that year, September 2 was immediately followed by September 14.

On Usenet, it is said that September 1993 (Eternal September) never ended.

In the United States, September is the third most common birth month, after August and July, which both have 31 days. Nine of the top 10 most common birthdays fall in September, with September 9 being the most common (and December 25 being the least common across the year), according to birth data collected by the National Center for Health Statistics between 1994 and 2014.

In recent decades, the number of warm temperature records in September has outpaced cold temperature records over a growing portion of Earth's surface.
In recent decades, the number of warm temperature records in September has outpaced cold temperature records over a growing portion of Earth's surface.
Chart shows changes in global average temperature annually in September of each year
Chart shows changes in global average temperature annually in September of each year

02Astronomy and astrology

The September equinox takes place in this month, and certain observances are organized around it. It is the Autumn equinox in the Northern Hemisphere, and the Vernal equinox in the Southern Hemisphere. The dates can vary from 21 September to 24 September (in UTC).

September is mostly in the sixth month of the astrological calendar (and the first part of the seventh), which begins at the end of March/Mars/Aries.

Sapphire, a birthstone of September
Sapphire, a birthstone of September
Forget-me-not, the birth flower of September
Forget-me-not, the birth flower of September

03Symbols

September's birthstone is the sapphire. The birth flowers are the forget-me-not, morning glory and aster. The zodiac signs are Virgo (until September 22) and Libra (September 23 onward).

POW☆MIA Flag.
POW☆MIA Flag.
School starts in September in many countries, such as Belgium
School starts in September in many countries, such as Belgium

04Observances

This list does not necessarily imply either official status or general observance.

Non-Gregorian

Month-long

United States

Food months

Movable Gregorian

First Wednesday

First Thursday

First Friday

First Sunday

First Sunday after September 4

Week of the first Monday

Week of September 10

First Monday

Nearest weekday to September 12

Second Saturday

Saturday after first Monday

Second Sunday

First Sunday after first Monday

Week of September 17

Third Tuesday

September 17 but observed on previous Friday if it falls on a Saturday or following Monday if on a Sunday

Third Friday

Third Saturday

Weekend of the week of September 17

Third Sunday

Week of Sunday before September 23

Week of September 22

Last week

Last full week

Third Monday

Pertaining to the September Equinox

Fourth Friday

Last Friday

Last Saturday

Last Sunday

Fourth Monday

Last Wednesday

Last weekday

Fixed Gregorian

Morning glories, a birth flower of September
Morning glories, a birth flower of September
Watch videos about SeptemberExplainers and documentaries on YouTube (opens in a new tab)

Sources and credits

This article is adapted from the Wikipedia article “September”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

Images, from Wikimedia Commons:

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