Winter is one of the four
seasons of temperate zones. Astronomically, it begins with the
winter solstice (around 21 December in the
Northern hemisphere, and 21 June in the
Southern hemisphere), and ends with the
spring equinox (around 21 March in the Northern hemisphere and 21 September in the Southern hemisphere). However, sometimes it is counted instead as the whole months of June, July and August in the Southern hemisphere and December, January and February in the Northern hemisphere.
See also: