January

January is the first month of the year in the Julian and Gregorian calendars and the first month to have the length of 31 days. The first day of the month is known as New Year's Day. It is, on average, the coldest month of the year within most of the Northern Hemisphere (where it is the second month of winter) and the warmest month of the year within most of the Southern Hemisphere (where it is the second month of summer). In the Southern hemisphere, January is the seasonal equivalent of July in the Northern hemisphere and vice versa.

Ancient Roman observances during this month include Cervula, and Juvenalia; celebrated January 1, as well as one of three Agonalia, celebrated January 9, and Carmentalia, celebrated January 11. These dates do not correspond to the modern Gregorian calendar.

January (in Latin, Ianuarius) is named after the Latin word for door (ianua), since January is the door to the year and an opening to new beginnings. The month is conventionally thought of as being named after Janus, the god of beginnings and transitions in Roman mythology, but according to ancient Roman farmers' almanacs Juno was the tutelary deity of the month.

Traditionally, the original Roman calendar consisted of 10 months totaling 304 days, winter being considered a month-less period. Around 713 BC, the semi-mythical successor of Romulus, King Numa Pompilius, is supposed to have added the months of January and February, so that the calendar covered a standard lunar year (354 days). Although March was originally the first month in the old Roman calendar, January became the first month of the calendar year either under Numa or under the Decemvirs about 450 BC (Roman writers differ). In contrast, each specific calendar year was identified by the names of the two consuls, who entered office on May 1 or March 15 until 153 BC, from when they entered office on January 1.

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