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A cold wave (known in some regions as a cold snap) is a weather phenomenon that is distinguished by a cooling of the air. Specifically, as used by the U.S. National Weather Service, a cold wave is a rapid fall in temperature within a 24-hour period requiring substantially increased protection to agriculture, industry, commerce, and social activities. The precise criterion for a cold wave is determined by the rate at which the temperature falls, and the minimum to which it falls. This minimum temperature is dependent on the geographical region and time of year.
A cold wave can cause death and injury to livestock and wildlife. Exposure to cold mandates greater caloric intake for all animals, including humans, and if a cold wave is accompanied by heavy and persistent snow, grazing animals may be unable to reach needed food and die of hypothermia or starvation. They often necessitate the purchase of foodstuffs to feed livestock at considerable cost to farmers.
Cold spells are associated with increased mortality rates in populations around the world. Both cold waves and heat waves cause deaths, though different groups of people may be susceptible to different weather events. In developed countries, more deaths occur during a heat wave than in a cold snap, though the mortality rate is higher in undeveloped regions of the world. Globally, more people die of cold weather than hot weather, due to the rise in diseases like cold, flu, and pneumonia.
Extreme winter cold often causes poorly insulated water pipelines and mains to freeze. Even some poorly protected indoor plumbing ruptures as water expands within them, causing much damage to property and costly insurance claims. Demand for electrical power and fuels rises dramatically during such times, even though the generation of electrical power may fail due to the freezing of water necessary for the generation of hydroelectricity. Some metals may become brittle at low temperatures. Motor vehicles may fail when antifreeze fails or motor oil gels, producing a failure of the transportation system. To be sure, such is more likely in places like Siberia and much of Canada that customarily get very cold weather.
Fires become even more of a hazard during extreme cold. Water mains may break and water supplies may become unreliable, making firefighting more difficult. The air during a cold wave is typically denser and thus contains more oxygen, so when air that a fire draws in becomes unusually cold it is likely to cause a more intense fire.
Winter cold waves that aren’t considered cold in some areas, but cause temperatures significantly below average for an area, are also destructive. Areas with subtropical climates may recognize unusual cold, perhaps barely freezing, temperatures, as a cold wave. In such places, plant and animal life is less tolerant of such cold as may appear rarely. The same winter temperatures that one associates with the norm for Kentucky, northern Utah, or Bavaria are catastrophic to winter crops in Florida or California that might be grown for wintertime consumption farther north, or to such all-year tropical or subtropical crops as citrus fruits. Likewise, abnormal cold waves that penetrate into tropical countries in which people do not customarily insulate houses or have either suitable clothing or reliable heating may cause hypothermia and even frostbite.
Cold waves that bring unexpected freezes and frosts during the growing season in mid-latitude zones can kill plants during the early and most vulnerable stages of growth, resulting in crop failure as plants are killed before they can be harvested economically. Such cold waves have caused famines. At times as deadly to plants as drought, cold waves can leave a land in danger of later brush and forest fires that consume dead biomass. One extreme was the so-called Year Without a Summer of 1816, one of several years during the 1810s in which numerous crops failed during freakish summer cold snaps after volcanic eruptions that reduced incoming sunlight.
In some places, such as Siberia, extreme cold requires that fuel-powered machinery to be used even part-time must be run continuously. Internal plumbing can be wrapped, and persons can often run water continuously through pipes. Energy conservation, difficult as it is in a cold wave, may require such measures as collecting people (especially the poor and elderly) in communal shelters. Even the homeless may be arrested and taken to shelters, only to be released when the hazard abates. Hospitals can prepare for the admission of victims of frostbite and hypothermia; schools and other public buildings can be converted into shelters.
People can stock up on food, water, and other necessities before a cold wave. Some may even choose to migrate to places of milder climates, at least during the winter. Suitable stocks of forage can be secured before cold waves for livestock, and livestock in vulnerable areas might be shipped from affected areas or even slaughtered. Smudge pots can bring smoke that prevents hard freezes on a farm or grove. Vulnerable crops may be sprayed with water that will paradoxically protect the plants by freezing and absorbing the cold from surrounding air.
Most people can dress appropriately and can even layer their clothing should they need to go outside or should their heating fail. They can also stock candles, matches, flashlights, and portable fuel for cooking and wood for fireplaces or wood stoves, as necessary. However caution should be taken as the use of charcoal fires for cooking or heating within an enclosed dwelling is extremely dangerous due to carbon monoxide poisoning. Adults must remain aware of the exposure that children and the elderly have to cold.
Historical cold waves
Contemporary cold waves (since 2001)
- February 2016 North American cold wave - Marked a temporary return of the polar vortex for the second week of February. Valentine's Day weekend gave the northeast a similar feeling from last year's February.
- January 2016 East Asia cold wave - Caused over 100 known deaths across East Asia, South Asia and Southeast Asia
- February 2015 North American cold wave – During the second half of February 2015, outstanding temperature records were broken in both sides of the spectrum. Extreme warm records were broken in the western half of the United States and extreme cold records were broken in the eastern half. In addition to the extreme cold wave at its most brutal in the Great Lakes, Mid-Atlantic, and New England, even as far south as the Deep South could not escape the wintry nightmare. In fact, excessive snowfall were reported as far south as Tupelo, Mississippi, Huntsville, Alabama, Shreveport, Louisiana, and even Flagstaff, Arizona. Freezing temperatures were even recorded as far south as Miami, Florida. The cold wave became widespread and all the remaining mild conditions from the west were pushed into northern Mexico. The cold wave even extended well into early March, with every U.S. state except Florida were covered in snow by March 1, 2015, and almost every body of water east of the Rocky Mountains were completely frozen solid. It was Winter Storm Thor, the winter storm that hammered the entire nation with his winter fury, hammering Kentucky the hardest, that was the one which ended the event. Shortly after Thor, hard-hit cities like Owensboro, Kentucky, and Nashville, Tennessee, have not only record snowfall, but subzero readings on the night of March 5-6, 2015. During that time, the entire Commonwealth of Kentucky was buried in massive snow and Kentucky Governor Steve Beshear have declared States of Emergencies twice, shortly after the events of Winter Storms Octavia (February 16, 2015) and Thor (March 4, 2015). Luckily, the pattern, or even the winter of 2014–15, finally ended in mid-March (with the exception of Winter Storm Ultima at the Mid-Atlantic on March 21 and one more winterlike push of chilly air a week later).
- November 2014 North American cold wave – Between November 8 and November 23, a polar vortex similar to earlier in 2014 has a temporary comeback, delivering the 2014-15 winter season's first three named winter storms (Astro, Bozeman, and Cato). Snowfall records were confirmed all over the Midwest and the Northeast, especially around the Great Lakes. Buffalo, New York, was among the hardest hit in the unseasonably wintry November. In addition to not being Thanksgiving yet, autumn colors were in the mix along with the deep winter snow.
- Early 2014 North American cold wave – On January 2–11, cold arctic air initially associated with a nor'easter invaded the central and eastern United States and Canada, east of the Rockies. Temperatures were even colder than the North Pole and the South Pole in many regions in the Upper Midwest and Canada. Temperatures reached as cold as −37 °F (−38 °C), and did not even get out of the negative double-digit temps in many places, including Chicago. The cold wave extended for a few more months, bringing a continuous pattern of record-low temperatures to most of the Central and upper eastern United States, before the pattern finally ended in early April.
- December 2013 North American cold wave – On December 1, the weakening of the polar vortex resulted in the jet stream shifting southward, which allowed abnormally cold temperatures to intrude the Central United States. On December 6, a daily record snowfall of 0.1 inches (2 mm) was set in the Dallas–Fort Worth metroplex, breaking the old record of trace amounts of snow, set in 1950. The cold wave continued into December 10, before the temperatures returned to a more stable range.
- Spring 2013 North American cold wave – Although the core winter of 2012-13 was fairly mild, both March and April were unusually cold across the Midwest, resulting in sharp temperature contrasts from March 2012 to March 2013 all over the United States and Canada. This late cold wave was unexpected because February and March of 2013 were both forecasted to be even milder and more springlike than February and March of 2012, but instead turned out with a near-average February and an unusually cold March. This same cold wave extended well into the month of April, as four named winter storms (Walda, Xerxes, Yogi, and Zeus) hammered through much of the northern United States, especially across Minnesota and the Dakotas. Minnesota's winter even extended well into early May with one more winter storm (Achilles). April is the month that usually symbolizes the majority of spring, but April 2013 was known to be snowy and wintry for the Upper Midwest, the Northern Plains, and the Prairie Provinces.
- Early 2012 European cold wave – As of February 11, 2012 at least 590 people died during a cold snap with temperatures falling below −35 °C (−31 °F) in some regions. Ukraine is the worst hit, with over 100 deaths related to the cold.
- Winter of 2010–2011 in Great Britain and Ireland – It was referred to as The Big Freeze by national media in both United Kingdom and Ireland and it was the coldest winter in Britain for thirty-one years with an average temperature of 1.51 °C (34.72 °F). The UK had its coldest December ever, since records began in 1910, with a mean temperature of −1 °C (30.2 °F). It easily broke the previous record of 0.1 °C (32.18 °F), set in December 1981.
- A cold wave affected much of the Deep South in the United States and Florida in January and February 2010.
- 2009-2010 European Cold Wave – At least ninety were confirmed dead after record low temperatures and heavy snowfall across Europe causes travel disruption to much of the continent including the British Isles, France, the Low Countries, Germany, Austria, Italy, Poland, the Baltic States, the Balkans, Ukraine and Russia. It was the coldest winter and longest cold spell for thirty years in the United Kingdom, whilst temperatures in the Italian Alpine peaks reached low to an extreme of −47 °C (−52.6 °F).
- Early 2009 European Cold Wave – Early January gave most of Europe, especially in central and south very cold temperatures. Some places like Germany, France, Italy, Romania and Spain had record cold temperatures well below 0 °C (32 °F). Most of the places were covered in snow and ice which caused school closings and airport delays. Large cities like Paris, Madrid, Berlin and even Marseille saw very cold temperatures with lots of snow and ice in Northern Italy, most of Germany, in northern Portugal and even along the coasts of the Mediterranean. In early February another cold front brought heavy snowfall to much of Western Europe with the heaviest snow falling in France, Northern Italy, the Low Countries and the United Kingdom, where parts of Southern England had seen the worst snowfall in over eighteen years causing widespread travel disruption particularly around London.
- 2008 Alaska Cold Wave – In early February, Alaska experienced the coldest temperatures for eight years, with Fairbanks nearing −50 °F (−45.6 °C) and Chicken, Alaska bottoming out at −72 °F (−57.8 °C), a mere eight °F (4.4 °C) away from the record of −80 °F (−62.2 °C). The first half of January also brought unusual cold weather and heavy snow to widespread regions of China and the Middle East.
- 2007 Argentine cold wave – An interaction with an area of low pressure systems across Argentina during the July 6, 7 and 8 of 2007, and the entry of a massive polar cold snap resulted in severe snowfalls and blizzards, and recorded temperatures below −32 °C (−26 °F). The cold snap advanced from the south towards the central zone of the country, continuing its displacement towards the north during Saturday, July 7. On Monday July 9, the simultaneous presence of very cold air, gave place to the occurrence of snowfalls. This phenomenon left at least 23 people dead.
- 2007 Northern Hemisphere cold wave – All of Canada and most of the United States underwent a freeze after a two-week warming that took place in late March and early April. Crops froze, wind picked up, and snow drizzled much of the United States. Some parts of Europe also experienced unusual cold winter-like temperatures, during that time.
- 2005-2006 European cold wave – Eastern Europe and Russia saw a very cold winter. Some of them saw their coldest on record or since the 1970s. Snow was an abundance in unusual places, such as in southern Spain and Northern Africa. All the winter months that season saw temperatures well below average across the continent.
- 2004-2005 Southern Europe cold wave – All areas of Southern Europe saw an unusually hard winter. This area saw an ice storm which have a 1 in 1000 chance of happening. This cold front caused snow in Algeria, which is extremely unusual. The south of Spain and Morocco also recorded freezing temperatures, and record freezing temperatures were observed on the north of Portugal and Spain.
- 2004 January cold outbreak, Northeast United States – New England was close to a record month when frequent Arctic fronts caused unusually cold weather. Boston had its coldest January since 1893 (19.7 °F or −6.8 °C), when it averaged 20.7 °F or −6.3 °C, and its lowest mean maximum at 27.2 °F or −2.7 °C. Virginia Beach had an unusually long period of below freezing weather. Some areas of northern New York saw 150 inches (3.81 m) of snow in a month. Many parts of the western and midwestern area of the country seen the effect as well.
20th-century cold waves
- 1997 Northern Plains cold air Outbreak – Mid-January across the Northern U.S. was one of the windiest on record. With a low of around −40 °F (−40.0 °C) in some places, wind caused bitterly cold wind chills sometimes nearing −80 °F (−62.2 °C). Northern parts of North Dakota saw up to 90 inches (2.29 m) of snow. This was one of the most severe cold-air outbreaks of the 1990s.
- 1996 Great Midwest cold outbreak – Late January and early February was Northern Minnesota’s coldest short term period on record. The record low of −60 °F (−51.1 °C) was recorded in Tower, Minnesota. Cities like Minneapolis experienced temperatures near −35 °F (−37.2 °C).
- 1995 White Earthquake in southern Chile – On August 1995 southern Chile was struck by a cold wave consisting in two successive cold fronts. Fodder scarcity caused a severe livestock starvation. Cows and sheep were also buried in snow. In parts of Tierra del Fuego up to 80% of the sheep died.
- 1994 Northern US/Southern Canada cold outbreak – January 1994 was the coldest month ever recorded or since January 1977 or February 1934 over many parts of the northeast and north-central United States, plus adjacent southeastern Canada. Many overnight record lows were set. Cold outbreaks continued into February but the severity eased somewhat. Detroit, Michigan saw the city’s coldest temperature since 1985.
- 1990 western United States – Extreme cold dropped down from Canada in the second half of December, causing record low temperatures up and down the West Coast, including one of California’s most damaging freezes on record.
- 1989 record cold start to December – In 1989, the central and eastern USA saw one of the coldest Decembers on record. A White Christmas occurred.
- 1985 Great Western cold air outbreak – February 1985 saw the contiguous US’ second-coldest temperature of −69 °F (−56.1 °C) in Peter Sinks, Utah. About a month of severe cold affected a large part of the nation. 1985 became the fourth coldest calendar year on record in the western USA.
- January 1985 US cold air outbreak – On January 21, 1985, it was so cold that President Ronald Reagan’s inauguration took place in the Capitol Rotunda. In addition to the cold in Washington, DC, the Miami Beach recorded its only frost since records began, lasting for a full three hours. Several other Southern cities set all-time record cold.
- December 1983 Great Plains cold wave – The contiguous US had its coldest ever Christmas in 1983. Severely cold winds blew in from Canada and about 70% of the month was colder than average. Many locations east of the Rockies broke December cold records on Christmas Eve. In addition to −23 °F (−30.6 °C) cold, the Sioux Falls area had 60 mph (97 km/h) winds bringing wind chills down to −70 °F (−56.7 °C). High temperatures did not even reach −10 °F (−23.3 °C) in northern Illinois during the days before Christmas. Temperatures dropped below 0 °F (−17.8 °C) on December 15 and remained there for over nine days at Sioux Falls. Minneapolis recorded an average temperature for the month of 3.7 °F (−15.7 °C), the coldest on record.
- 1982 cold air outbreak – January 1982 was very cold. The 1981 AFC Championship Game, held in Cincinnati was nicknamed the ”Freezer Bowl“ due to the −9 °F (−22.8 °C) temperature and −59 °F (−50.6 °C) wind chill. The following week’s events was also known as Cold Sunday.
- 1970s – In the last three years of the 1970s almost all of the conterminous United States had at least one winter with a memorable cold wave, and the winter of 1978-1979 was the coldest on record in the lower 48, with everywhere bar normally frigid upstate Maine experiencing well below average temperatures.
- Winter of 1968–69 in Central Asia – Central Asia and western Siberia saw by far their coldest winter on record in 1968-1969, and in Central Asia also their wettest, producing record low temperature, severe blizzards and avalanches, numerous plant deaths and record spring flooding.
- 1966 Western Canadian cold wave – January 1966 was the coldest January on record in the Yukon and the coldest since 1950 or 1875 in the Prairie Provinces, and the severe cold continued into March, when Winnipeg recorded its most severe winter snowstorm on record.
- Winter of 1962–63 in the United Kingdom – The winter of 1962-1963 was the coldest for 223 years in England, and the freeze was accompanied by strong easterly winds and the freezing of rivers and streams.
- 1956 European cold wave – February 1956 was the coldest month of the twentieth century over large areas of Western Europe, with mean temperatures below 0 °C (32 °F) as far south as Marseilles being utterly unprecedented in records dating back into the eighteenth century.
- 1950 Northwest North American cold wave – January 1950 saw unprecedented cold and snowfall in the Pacific Northwest, with normally mild Seattle and Portland, Oregon both falling below 0 °F (−17.8 °C) and receiving extremely heavy snow that disrupted transport and schooling as it could not be removed easily. Western Canada saw by far its coldest month on record, leading to severe damage to fruit crops in the Okanagan Valley, the freezing of Okanagan Lake for the only time since 1862, and Calgary’s only month where temperatures remained below 32 °F (0 °C) throughout.
- 1949 Western North American cold wave – The winter of 1948-1949 was the coldest since 1891 over the Western United States and saw record snowfall, ice storms as far south as Texas, and constant disruptions to surface transport, along with large losses in livestock and crops.
- Winter of 1941-42 in Eastern Europe – The winter of 1941-1942 was the coldest of the twentieth century in most of Eastern Europe (e.g. Moscow) and was the last of a succession of abnormally cold winters there that affected the course of World War II.
- 1937 Western United States cold wave – January 1937 was the coldest month on record in the West and saw snowfall as far south as the hot desert city of Yuma, Arizona for one of only two occasions on record. California and Nevada saw their lowest temperatures on record – −45 °F (−42.8 °C) at Boca on January 20 and −50 °F (−45.6 °C) at San Jacinto on January 8.
- 1936 North American cold wave – The cold wave of 1936 was the only cold wave of the 1930s to severely impact the United States east of the hundredth meridian.
- 1933 Western United States cold wave – The winter of 1932-1933 was the second or third coldest on record in most of the West (the coldest on record in Arizona) and saw record cold temperatures in Oregon, Wyoming and Texas between February 7 and 10, when sixty deaths were blamed on extreme cold and ice storms.
- 1910s – The severe 1912 United States cold wave caused the longest recorded period of below-0 °F or −17.8 °C weather. The “extended winter” (October to March) of 1916-1917 was the coldest on record in the West and Midwest, whilst the 1917-1918 winter was very frigid across the East and created a heating fuel crisis equalled only in January 1977.
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