Meteorologists consider winter to be the three coldest months of December

In the United Kingdom, meteorologists consider winter to be the three coldest months of December, January and February.[17] In Scandinavia, winter in one tradition begins on 14 October and ends on the last day of February.[18] In Russia, calendar winter is w

idely regarded to start on 1 December[19] and end on 28 February.[20] In many countries in the Southern Hemisphere, including Australia,[21][22] New Zealand,[23] and South Africa, winter begins on 1 June and ends on 31 August. In Celtic nations such as Ireland (using the Irish calendar) and in Scandinavia, the winter solstice is traditionally considered as midwinter,

with the winter season beginning 1 November, on All Hallows, or Samhain. Winter ends and spring begins on Imbolc, or Candlemas, which is 1 or 2 February. This system of seasons is based on the length of days exclusively. (The three-month period of the shortest days and weakest solar radiation occurs during November, December and January in the Northern Hemisphere and May, June and July in the Southern Hemisphere.)

Also, many mainland European countries tended to recognize Martinmas or St. Martin’s Day (11 November), as the first calendar day of winter.[24] The day falls at the midpoint between the old Julian equinox and solstice dates. Also, Valentine’s Day (14 February) is recognized by some countries as heralding the first rites of spring, such as flowers blooming.[25]