For other uses, see Winter (disambiguation).
"Winters" redirects here. For other uses, see Winters (disambiguation).
A snow-covered park in front of the Cathedral of Learning in Pittsburgh, Pennsylvania, during winter

Winter is the coldest season of the year in polar and temperate climates, between autumn and spring. Winter is caused by the axis of the Earth in that hemisphere being oriented away from the Sun. Different cultures define different dates as the start of winter, and some use a definition based on weather. When it is winter in the Northern Hemisphere, it is summer in the Southern Hemisphere, and vice versa. In many regions, winter is associated with snow and freezing temperatures. The moment of winter solstice is when the sun's elevation with respect to the North or South Pole is at its most negative value (that is, the sun is at its farthest below the horizon as measured from the pole), meaning this day will have the shortest day and the longest night. The earliest sunset and latest sunrise dates outside the polar regions differ from the date of the winter solstice, however, and these depend on latitude, due to the variation in the solar day throughout the year caused by the Earth's elliptical orbit (see earliest and latest sunrise and sunset).


The English word "winter" comes from the Proto-Indo-European word "wend," which stands for water.[1]


Conifer forest in the Pillapalu, Estonia, in January 2014

The tilt of the Earth's axis relative to its orbital plane plays a big role in the weather. The Earth is tilted at an angle of 23.44° to the plane of its orbit, and this causes different latitudes on the Earth to directly face the Sun as the Earth moves through its orbit. It is this variation that primarily brings about the seasons. When it is winter in the Northern Hemisphere, the Southern Hemisphere faces the Sun more directly and thus experiences warmer temperatures than the Northern Hemisphere. Conversely, winter in the Southern Hemisphere occurs when the Northern Hemisphere is tilted more toward the Sun. From the perspective of an observer on the Earth, the winter Sun has a lower maximum altitude in the sky than the summer Sun.

During winter in either hemisphere, the lower altitude of the Sun causes the sunlight to hit that hemisphere at an oblique angle. In regions experiencing winter, the same amount of solar radiation is spread out over a larger area. This effect is compounded by the larger distance that the light must travel through the atmosphere, allowing the atmosphere to dissipate more heat. Compared with these effects, the changes in the distance of the earth from the sun are negligible.

The manifestation of the meteorological winter (freezing temperatures) in the northerly snow–prone parallels is highly variable depending on elevation, position versus marine winds and the amount of precipitation. A case of point is in Canada which is a country normally associated with its tough winters. Winnipeg on the Great Plains at a relative distance from large bodies of water has a January high of −11.3 °C (11.7 °F) and a low of −21.4 °C (−6.5 °F).[2] In comparison, Vancouver on the coast with a marine influence from moderating Pacific winds has a January low of 1.4 °C (34.5 °F) with days well above freezing at 6.9 °C (44.4 °F).[3] Both areas are on the 49th parallel north and in the same western half of the continent. A similar effect, although with less extreme differentials, is found in Europe where in spite of the northerly latitude of the islands, the British Isles has not a single non-mountain weather station with a below-freezing mean temperature.[4]

Meteorological reckoning

Animation of snow cover changing with the seasons
The Old Town of Tallinn, Estonia, full of snow on 1 January 2010

Meteorological Reckoning is the method of measuring the winter season used by meteorologists based on "sensible weather patterns" for record keeping purposes,[5] so the start of meteorological winter varies with latitude.[6] Winter is often defined by meteorologists to be the three calendar months with the lowest average temperatures. This corresponds to the months of December, January and February in the Northern Hemisphere, and June, July and August in the Southern Hemisphere. The coldest average temperatures of the season are typically experienced in January or February in the Northern Hemisphere and in June, July or August in the Southern Hemisphere. Nighttime predominates in the winter season, and in some regions winter has the highest rate of precipitation as well as prolonged dampness because of permanent snow cover or high precipitation rates coupled with low temperatures, precluding evaporation. Blizzards often develop and cause many transportation delays. Diamond dust, also known as ice needles or ice crystals, forms at temperatures approaching −40 °F (−40 °C) due to air with slightly higher moisture from aloft mixing with colder, surface based air.[7] They are made of simple ice crystals that are hexagonal in shape.[8] The Swedish meteorological institute (SMHI) define winter as when the daily mean temperatures go below 0 °C (32 °F) for five consecutive days.[9] According to the SMHI, winter in Scandinavia is more pronounced when Atlantic low–pressure systems take more southerly and northerly routes, leaving the path open for high–pressure systems to come in and cold temperatures to occur. As a result, the coldest January on record in 1987 was also the sunniest in Stockholm.[10][11]

Accumulations of snow and ice are commonly associated with winter in the Northern Hemisphere, due to the large land masses there. In the Southern Hemisphere, the more maritime climate and the relative lack of land south of 40°S makes the winters milder; thus, snow and ice are less common in inhabited regions of the Southern Hemisphere. In this region, snow occurs every year in elevated regions such as the Andes, the Great Dividing Range in Australia, and the mountains of New Zealand, and also occurs in the southerly Patagonia region of South America. Snow occurs year-round in Antarctica.

Astronomical and other calendar-based reckoning

Winter snowfall in Jerusalem, 31 January 2008
Winter in La Carlota, Córdoba, Argentina 9 July 2007
Winter in Carraroe, Galway, Ireland, on 25 December 2010
Winter in Owensboro, Kentucky, United States 16 February 2015
In the mid-latitudes and arctic, winter is associated with snow and ice
In the southern hemisphere, winter extends from June to September, as seen in this August 2001 picture, taken in the town of São Joaquim in the southern highlands of Brazil.
The Port of Hamburg, Germany, on 6 January 2010
Heavy snowfall during the night in Pant Glas, Gwynedd, Wales on 20 February 2010
A morning after a cold night in the United States
Nieve Ranelagh, Argentina

In the Northern Hemisphere, some authorities define the period of winter based on astronomical fixed points (i.e. based solely on the position of the Earth in its orbit around the sun), regardless of weather conditions. In one version of this definition, winter begins at the winter solstice and ends at the vernal equinox.[12] These dates are somewhat later than those used to define the beginning and end of the meteorological winter – usually considered to span the entirety of December, January, and February in the Northern Hemisphere and June, July, and August in the Southern.[13]

Astronomically, the winter solstice, being the day of the year which has fewest hours of daylight, ought to be the middle of the season,[14][15] but seasonal lag means that the coldest period normally follows the solstice by a few weeks. In some cultures, the season is regarded as beginning at the solstice and ending on the following equinox[16][17] – in the Northern Hemisphere, depending on the year, this corresponds to the period between 21 or 22 December and 19, 20 or 21 March. In the UK, meteorologists consider winter to be the three coldest months of December, January and February.[18]

In Scandinavia, winter in one tradition begins on 14 October and ends on the last day of February.[19] In Russia, currently calendar winter starts on 1 December and lasts through to the end of February, though traditionally it was reckoned from the Christmas (25 December in Julian calendar, or 7 January in Gregorian) until the Annunciation (25 March in Julian).[20] In many countries in the Southern Hemisphere, including Australia,[21][22] New Zealand 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 tend to recognize Martinmas or St. Martin's Day (11 November), as the first calendar day of winter. The day falls at 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.

In Chinese astronomy and other East Asian calendars, winter is taken to commence on or around 7 November, with the Jiéqì (known as 立冬 lì dōng—literally, "establishment of winter").

The three-month period associated with the coldest average temperatures typically begins somewhere in late November or early December in the Northern Hemisphere and lasts through late February or early March. This "thermological winter" is earlier than the solstice delimited definition, but later than the daylight (Celtic) definition. Depending on seasonal lag, this period will vary between climatic regions.

Cultural influences such as Christmas creep may have led to the winter season being perceived as beginning earlier in recent years, although high latitude countries like Canada are usually well into their real winters before the December solstice.

Ecological reckoning and activity

The snowshoe hare, and some other animals, change color in winter.

Ecological reckoning of winter differs from calendar-based by avoiding the use of fixed dates. It is one of six seasons recognized by most ecologists who customarily use the term hibernal for this period of the year (the other ecological seasons being prevernal, vernal, estival, serotinal, and autumnal).[23] The hibernal season coincides with the main period of biological dormancy each year whose dates vary according to local and regional climates in temperate zones of the Earth. The appearance of flowering plants like the crocus can mark the change from ecological winter to the prevernal season as early as late January in mild temperate climates.

To survive the harshness of winter, many animals have developed different behavioral and morphological adaptations for overwintering:

Some annual plants never survive the winter. Other annual plants require winter cold to complete their life cycle, this is known as vernalization. As for perennials, many small ones profit from the insulating effects of snow by being buried in it. Larger plants, particularly deciduous trees, usually let their upper part go dormant, but their roots are still protected by the snow layer. Few plants bloom in the winter, one exception being the flowering plum, which flowers in time for Chinese New Year. The process by which plants become acclimated to cold weather is called hardening.

Exceptionally cold winters

River Thames frost fair, 1683

Other historically significant winters

A frozen lake in the winter of 2010
Winter in Rego Park, Queens, New York

Humans and winter

Humans evolved in tropical climates, and met cold weather as they migrated into Eurasia, although earlier populations certainly encountered Southern Hemisphere winters in Southern Africa. Micro-evolution in Caucasian, Asiatic and Inuit people show some adaptation to the climate.

Winter and human health

Humans are sensitive to cold, see hypothermia. Snowblindness, norovirus, seasonal depression, slipping on black ice and falling icicles are other health concerns associated with cold and snowy weather. In the Northern Hemisphere, it is not unusual for homeless people to die from hypothermia in the winter.

One of the most common diseases associated with winter is influenza. Symptoms include: headache, fever, muscle pains, sinus infection, fatigue, dizziness, cough, and loss of appetite.


Allegory of Winter by Jerzy Siemiginowski-Eleuter with Aeolus' Kingdom of the Winds, 1683, Wilanów Palace

In Persian culture, the winter solstice is called Yaldā (meaning: birth) and it has been celebrated for thousands of years. It is referred to as the eve of the birth of Mithra, who symbolised light, goodness and strength on earth.

In Greek mythology, Hades kidnapped Persephone to be his wife. Zeus ordered Hades to return her to Demeter, the goddess of the Earth and her mother. However, Hades tricked Persephone into eating the food of the dead, so Zeus decreed that Persephone would spend six months with Demeter and six months with Hades. During the time her daughter is with Hades, Demeter became depressed and caused winter.

In Welsh mythology, Gwyn ap Nudd abducted a maiden named Creiddylad. On May Day, her lover, Gwythr ap Greidawl, fought Gwyn to win her back. The battle between them represented the contest between summer and winter.

In Bengali, the advent of winter is often expressed by the sentence "Sheeter buri ashchhe dheye" which means "the winter old woman is coming fast". This is used especially when it is said to a child.


See also


  2. "Canadian Climate Normals 1981-2010 Station Data for Winnipeg". Environment Canada. Retrieved 8 August 2015.
  3. "Canadian climate normals 1981-2010 Station Data for Vancouver". Environment Canada. Retrieved 8 August 2015.
  4. "UK climate - Station Map". Met Office. Retrieved 8 August 2015.
  5. Huttner, Paul (6 December 2007). "Instant meteorological winter". Minnesota Public Radio. Retrieved 22 December 2011.
  6. "Winter's Been Here Despite What the Calendar Says". NOAA Magazine. 22 December 2003. Retrieved 22 December 2011.
  7. Glossary of Meteorology (June 2000). "Diamond Dust". American Meteorological Society. Retrieved 21 January 2010.
  8. Kenneth G. Libbrecht (2001). "Morphogenesis on Ice: The Physics of Snow Crystals" (PDF). Engineering & Science. California Institute of Technology (1): 12. Retrieved 21 January 2010.
  9. "Vinter" (in Swedish). SMHI. Retrieved 31 July 2015.
  10. "Precipitation, Sunshine & Radiation for January 2015 (all-time records section)" (PDF) (in Swedish). SMHI. Retrieved 31 July 2015.
  11. "Temperature & Wind - January 2015 (all-time records section)" (PDF) (in Swedish). SMHI. Retrieved 31 July 2015.
  12. . In Standards: The Seasons. Retrieved 20 December 2012, from
  13. . In When does Autumn start? Defining seasons. Retrieved 20 December 2012
  14. Ball, Sir Robert S (1900). Elements of Astronomy. London: The MacMillan Company. p. 52. ISBN 9781440053238.
  15. Heck, Andre (2006). Organizations and strategies in Astronomy Volume 7. Springer. p. 14. ISBN 1-4020-5300-2.
  16. winter. (2009). In Encyclopædia Britannica. Retrieved 13 May 2009, from Encyclopædia Britannica Online
  17. solstice. (2009). In Encyclopædia Britannica. Retrieved 13 May 2009, from Encyclopædia Britannica Online
  18. Meteorological Glossary (Sixth ed.). London: HMSO. 1991. p. 260. ISBN 0-11-400363-7.
  19. Første vinterdag. (2009). The Norwegian Meteorological Institute. Retrieved 31 August 2009.
  20. Иван Забелин. Домашний быт русских царей в XVI и XVII столетиях. — М.: Транзиткнига, 2005. — 162 с. — ISBN 5-9578-2773-8, in Russian
  21. Meteorological Glossary. Retrieved 21 June 2009 from Australian Bureau of Meteorology
  22. Hamilton, Daniel (2 June 2009). "Images from around Australia on first day of Winter 2009". Retrieved 23 May 2012.
  23. Michael Allaby (1999). "A Dictionary of Zoology". Retrieved 30 May 2012.
  24. Cormac Ó Gráda (2009). "Famine: a short history". Princeton University Press. p.23. ISBN 0-691-12237-7
  25. "Winter 1947 in the British Isles". Retrieved 22 December 2011.
  26. Grant, Ash (1 February 2010). "Top 10 Worst Blizzards U.S. History". Top 10 Worst Blizzards U.S. History. Ash Grant. Retrieved 4 December 2014.

Further reading

External links

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