January is the first month of the year in the Julian and Gregorian calendars. Its length is 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 These dates do not correspond to the modern Gregorian calendar.
January in Latin, Ianuarius is named after Janus , the god of beginnings and transitions in Roman mythology. Traditionally, the original Roman calendar consisted of 10 months totaling days, winter being considered a month-less period. Around 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 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 BC Roman writers differ.
