October is the tenth month of the year in the Julian and Gregorian calendars. Its length is 31 days. The eighth month in the old calendar of Romulus c. 750 BC, October retained its name (from Latin and Greek ôctō meaning "eight") after January and February were inserted into the calendar that had originally been created by the Romans. In Ancient Rome, one of three Mundus patet would take place on October 5, Meditrinalia October 11, Augustalia on October 12, October Horse on October 15, and Armilustrium on October 19. These dates do not correspond to the modern Gregorian calendar. Among the Anglo-Saxons, it was known as Winterfylleth (Ƿinterfylleþ), because at this full moon, winter was supposed to begin. October is commonly associated with the season of spring in parts of the Southern Hemisphere, and autumn in parts of the Northern Hemisphere, where it is the seasonal equivalent to April in the Southern Hemisphere and vice versa.

Symbols

October's birthstones are the tourmaline and opal. Its birth flower is the calendula. The zodiac signs are Libra (until October 22) and Scorpio (from October 23 onward).

Observances

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

Non-Gregorian: dates

(All Baha'i, Islamic, and Jewish observances begin at the sundown prior to the date listed, and end at sundown of the date in question unless otherwise noted.)

Month-long

United States

The last two to three weeks in October (and, occasionally, the first week of November) are normally the only time of the year during which all of the "Big Four" major professional sports leagues in the U.S. and Canada schedule games; the National Basketball Association begins its preseason and about two weeks later starts the regular season, the National Hockey League is in the first month of its regular season, the National Football League is about halfway through its regular season, and Major League Baseball is in its postseason with the League Championship Series and World Series. Days on which all four leagues play are colloquially known as a sports equinox.

United States, health-related

United States, culinary

Movable dates

First Sunday

First Monday

First Tuesday

First Wednesday

First Thursday

First Friday

First full week

Second Sunday

Second Monday

Second Tuesday

Second Wednesday

Wednesday of second full week in October

Second Thursday

Second Friday

Second Saturday

Week of October 10

Second Week of October

Third Sunday

Third Monday

Third Thursday

Third Saturday

Fourth Monday

Fourth Wednesday

Fourth Friday

Fourth Saturday

Week of Fourth Wednesday

Last Monday

Last Friday

Last Sunday

Fixed

Miscellaneous