Winter is the coldest season of the year in polar and temperate zones
(winter does not occur in the tropical zone). It occurs after autumn
and before spring in each year.
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). The day on which this occurs has the
shortest day and the longest night, with a daylength increasing and
nightlength decreasing as the season processes after the solstice. 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).
3 Meteorological reckoning
4 Astronomical and other calendar-based reckoning
5 Ecological reckoning and activity
6 Exceptionally cold winters
7 Other historically significant winters
8 Humans and winter
Winter and human health
10 See also
12 Further reading
13 External links
The English word "winter" comes from the
"wend," relating to water.
See also: Effect of
Sun angle on climate
The tilt of the Earth's axis relative to its orbital plane plays a
large role in the formation of weather. The Earth is tilted at an
angle of 23.44° to the plane of its orbit, causing different
latitudes to directly face the
Sun as the Earth moves through its
orbit. This variation brings about seasons. When it is winter in the
Northern Hemisphere, the
Southern Hemisphere faces the
directly and thus experiences warmer temperatures than the Northern
Hemisphere. Conversely, winter in the
Southern Hemisphere occurs when
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 in point is Canada, a country normally
associated with 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). 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). 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
Animation of snow cover changing with the seasons
Winter in the
Southern Hemisphere in Tierra del Fuego, Argentina
Meteorological reckoning is the method of measuring the winter season
used by meteorologists based on "sensible weather patterns" for record
keeping purposes, so the start of meteorological winter varies with
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. They are made of simple ice
crystals that are hexagonal in shape. The Swedish meteorological
institute (SMHI) define winter as when the daily mean temperatures go
below 0 °C (32 °F) for five consecutive days. 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.
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
Snow occurs year-round in Antarctica.
Astronomical and other calendar-based reckoning
In the mid-latitudes and polar regions, winter is associated with snow
In the southern hemisphere, winter extends from June to September
São Joaquim in the southern highlands of Brazil.
Sea ice in the Port of Hamburg, Germany.
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. 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.
Astronomically, the winter solstice, being the day of the year which
has fewest hours of daylight, ought to be in the middle of the
season, 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 – 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. In Scandinavia, winter
in one tradition begins on 14 October and ends on the last day of
February. 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
March in Julian). In many countries in the Southern Hemisphere,
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.
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
St. Martin's Day
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
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
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.
Since by almost all definitions valid for the Northern hemisphere,
winter spans 31 December and 1 January, the season is split across
years, just like summer in the Southern hemisphere. Each calendar year
includes parts of two winters. This causes ambiguity in associating a
winter with a particular year, e.g. "
Winter 2018". Solutions for this
problem include naming both years, e.g. "
Winter 18/19", settling on
the year the season starts in or on the year most of its days belong
to, which is the later year for most definitions.
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). 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:
Migration is a common effect of winter upon animals, notably birds.
However, the majority of birds do not migrate—the cardinal and
European robin, for example. Some butterflies also migrate seasonally.
Hibernation is a state of reduced metabolic activity during the
winter. Some animals "sleep" during winter and only come out when the
warm weather returns; e.g., gophers, frogs, snakes, and bats.
Some animals store food for the winter and live on it instead of
hibernating completely. This is the case for squirrels, beavers,
skunks, badgers, and raccoons.
Resistance is observed when an animal endures winter but changes in
ways such as color and musculature. The color of the fur or plumage
changes to white (in order to be confused with snow) and thus retains
its cryptic coloration year-round. Examples are the rock ptarmigan,
Arctic fox, weasel, white-tailed jackrabbit, and mountain hare.
Some fur-coated mammals grow a heavier coat during the winter; this
improves the heat-retention qualities of the fur. The coat is then
shed following the winter season to allow better cooling. The heavier
coat in winter made it a favorite season for trappers, who sought more
Snow also affects the ways animals behave; many take advantage of the
insulating properties of snow by burrowing in it. Mice and voles
typically live under the snow layer.
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
Thames frost fair, 1683
1683–1684, "The Great Frost", when the Thames, hosting the River
Thames frost fairs, was frozen all the way up to the London Bridge and
remained frozen for about two months. Ice was about 27 cm
(11 in) thick in London and about 120 cm (47 in) thick
in Somerset. The sea froze up to 2 miles (3.2 km) out around the
coast of the southern North Sea, causing severe problems for shipping
and preventing use of many harbours.
1739–1740, one of the most severe winters in the UK on record. The
Thames remained frozen-over for about 8 weeks. The Irish famine of
1740–1741 claimed the lives of at least 300,000 people.
1816 was the Year Without a
Summer in the Northern Hemisphere. The
unusual coolness of the winter of 1815–1816 and of the following
summer was primarily due to the eruption of
Mount Tambora in
Indonesia, in April 1815. There were secondary effects from an unknown
eruption or eruptions around 1810, and several smaller eruptions
around the world between 1812 and 1814. The cumulative effects were
worldwide, but were especially strong in the Eastern United States,
Atlantic Canada, and Northern Europe. Frost formed in May in New
England, killing many newly planted crops, and the summer never
Snow fell in New York and Maine in June, and ice formed in
lakes and rivers in July and August. In the UK, snow drifts remained
on hills until late July, and the
Thames froze in September.
Agricultural crops failed and livestock died in much of the Northern
Hemisphere, resulting in food shortages and the worst famine of the
1887–1888, there were record cold temperatures in the Upper Midwest,
heavy snowfalls worldwide, and amazing storms, including the
Blizzard of 1888 (in the Midwest in January), and the
Blizzard of 1888 (in the Eastern US and
Canada in March).
In Europe, the winters of early 1947, February 1956, 1962–1963,
1981–1982 and 2009–2010 were abnormally cold. The UK winter of
1946–1947 started out relatively normal, but became one of the
snowiest UK winters to date, with nearly continuous snowfall from late
January until March.
in South America the winter 1975 was one of the strongest, occurring
record of snow in zones at 25°S in cities of low altitude, with
registration of -17°C (1,4°F) in some parts of southern Brazil.
In the eastern United States and Canada, the winter of 2013–2014 and
the second half of February 2015 were abnormally cold. However, the
winter of 2014–2015 did have a balmy December and a normal January.
Other historically significant winters
1310–1330, many severe winters and cold, wet summers in Europe –
the first clear manifestation of the unpredictable weather of the
Little Ice Age
Little Ice Age that lasted for several centuries (from about 1300 to
1900). The persistently cold, wet weather caused great hardship, was
primarily responsible for the Great Famine of 1315–1317, and
strongly contributed to the weakened immunity and malnutrition leading
up to the
Black Death (1348–1350).
1600–1602, extremely cold winters in Switzerland and Baltic region
after eruption of
Huaynaputina in Peru in 1600.
1607–1608, in North America, ice persisted on Lake Superior until
June. Londoners held their first frost fair on the frozen-over River
1622, in Turkey, the
Golden Horn and southern section of Bosphorus
1690s, extremely cold, snowy, severe winters. Ice surrounded Iceland
for miles in every direction.
1779–1780, Scotland's coldest winter on record, and ice surrounded
Iceland in every direction (like in the 1690s). In the United States,
a record five-week cold spell bottomed out at −20 °F
(−29 °C) at Hartford, Connecticut, and −16 °F
(−27 °C) in New York City. Hudson River and New York's harbor
Thames partially froze, and snow remained on the
ground for months. In February 1784, the North Carolina was frozen in
1794–1795, severe winter, with the coldest January in the UK and
lowest temperature ever recorded in London: −21 °C
(−6 °F) on 25 January. The cold began on
Christmas Eve and
lasted until late March, with a few temporary warm-ups. The Severn and
Thames froze, and frost fairs started up again. The French army tried
to invade the Netherlands over its frozen rivers, while the Dutch
fleet was stuck in its harbor. The winter had Easterlies (from
Siberia) as its dominant feature.
1813–1814, severe cold, last freeze-over of Thames, and last frost
fair. (Removal of old London Bridge and changes to river's banks made
freeze-overs less likely.)
1883–1888, colder temperatures worldwide, including an unbroken
string of abnormally cold and brutal winters in the Upper Midwest,
related to the explosion of
Krakatoa in August 1883. There was snow
recorded in the UK as early as October and as late as July during this
1976–1977, one of the coldest winters in the US in decades.
1985, Arctic outbreak in US resulting from shift in polar vortex, with
many cold temperature records broken.
2002–2003 was an unusually cold winter in the Northern and Eastern
2010–2011, persistent bitter cold in the entire eastern half of the
US from December onward, with few or no mid-winter warm-ups, and with
cool conditions continuing into spring.
La Niña and negative Arctic
oscillation were strong factors. Heavy and persistent precipitation
contributed to almost constant snow cover in the Northeastern US which
finally receded in early May.
2011 was one of the coldest on record in
New Zealand with sea level
snow falling in
Wellington in July for the first time in 35 years and
a much heavier snowstorm for 3 days in a row in August.
2011–2012, one of the warmest winters.
Christmas Day 2011 was the
Christmas in Ireland, as observed by the Armagh
Humans and winter
Humans evolved in tropical climates, and met cold weather as they
migrated into Eurasia, although earlier populations certainly
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.
Jerzy Siemiginowski-Eleuter with Aeolus' Kingdom
of the Winds, 1683, Wilanów Palace
In Persian culture, the winter solstice is called
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,
Persephone to be his wife. Zeus
Hades to return her to Demeter, the goddess of the Earth and
her mother. However,
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
Demeter became depressed and caused winter.
In Welsh mythology,
Gwyn ap Nudd
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
Old Man Winter
Matariki is a festival in
New Zealand that celebrates the Maori New
Year in early winter (Late May and June), honouring the
Winter festivals (list)
Winter Olympic Games
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Media related to
Winter (category) at Wikimedia Commons
Quotations related to
Winter at Wikiquote
Cold weather travel guide from Wikivoyage
The dictionary definition of winter at Wiktionary
Harmattan (West Africa)