The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject.(April 2022)
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A cold wave (known in some regions as a cold snap, cold spell or Arctic 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 criteria for a cold wave are 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.
In the United States, a cold spell is defined as the national average high temperature dropping below 20 °F (−7 °C). A cold wave of sufficient magnitude and duration may be classified as a cold air outbreak (CAO).
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. More deaths occur during a cold wave than in a heat wave, though the mortality rate is higher in undeveloped regions of the world. Globally, more people die during hot weather than cold weather. 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.
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[ citation needed ]. However, snow may stop spreading of fires, especially wildfires.
Winter cold waves that are not considered cold in some areas, but cause temperatures significantly below average for an area, are also destructive. Areas with subtropical climates may recognize a cold wave at higher temperatures than other, colder areas of the globe. The cold wave may be recognized at barely freezing temperatures, as these are still unusually cold for the region, and plant and animal life will be less tolerant of such cold. The same winter temperatures that one associates with the norm for Colorado, Ohio, or Bavaria are catastrophic to crops in places like Florida, California, or parts of South America that grow fruit and vegetables in winter.
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 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.
Recent research suggests a possible link between cold waves and extratropical cyclogenesis.
In some places, such as Siberia, extreme cold requires that fuel-powered machinery intended to be used occasionally must be run continually. 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 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.
Novosibirsk reached a low of -41 °C. Beijing recorded a low of -19.6 °C which was the coldest since 1966. Seoul also recorded -18.6 °C in January 8 which was the tie record with 2001 and the coldest since 1986. Over 200 cm of snow fell in western Japan along the Japan Sea coast.
The first snowfall began on 17 December 2009, before a respite over the Christmas period. −17.6 °C (0.3 °F) in Greater Manchester, England. The snow spread to Southern England on 6 January and by 7 January the United Kingdom was blanketed in snow, which was captured by NASA's Terra satellite. The thaw came a week later, as temperatures started to increase. The winter weather brought widespread transport disruption, school closures, power failures, the postponement of sporting events and 25 deaths. A low of −22.3 °C (−8.1 °F) was recorded in Altnaharra, Scotland on 8 January 2010. Overall it was the coldest winter since 1978–79, with a mean temperature of 1.5 °C (34.7 °F).The most severe snowy weather began on 5 January in North West England and west Scotland with temperatures hitting a low of
1904 was the coolest year on record.
Oymyakon is a rural locality in Oymyakonsky District of the Sakha Republic, Russia, located in the Yana-Oymyakon Highlands, along the Indigirka River, 30 km (19 mi) northwest of Tomtor on the Kolyma Highway. By winter average temperatures, it is the coldest permanently inhabited settlement on Earth.
The climate of Salt Lake City, Utah features cold and snowy winters, hot and dry summers, and modest to light seasonal rainfall. Lying in the Salt Lake Valley, the city is surrounded by mountains and the Great Salt Lake. Under the Köppen climate classification, Salt Lake City has either a humid subtropical climate (Cfa) or a humid continental climate (Dfa) depending on which variant of the system is used, though it borders on a Mediterranean climate (Csa) or dry-summer continental climate (Dsa) as summers are quite dry.
The 2006 European cold wave was an unusual and deadly cold wave which resulted in abnormal winter conditions over much of Europe. Southern Europe saw cold and snow, while places in northern Norway saw abnormally mild conditions. The phenomenon started in early January 2006, in the region of the Polar Urals, with temperatures nosediving below -50°C, and extended to west Russia, then Central Europe where parts of Poland, Slovakia, and Austria saw temperatures drop below -30 °C. The cold wave resulted in the deaths of up to 50 people in Russia, and a significant death toll in Eastern Europe, including Ukraine, Moldova, and Romania. The abnormal conditions gradually abated towards the end of the month. According to Munich Re reinsurance company, it was the deadliest cold snap between 1980 and 2011, causing 790 fatalities throughout Europe. According to the International Federation of Red Cross and Red Crescent Societies, there were 884 deaths in Ukraine, 135 in Moscow, 13 in Moldova and 5 in Belarus, and over 20,000 cases of frostbite were treated in the region's hospitals. The damage to Russian crops due to severe frost was estimated at $929 million.
The cold wave of 1978 was a weather event that occurred in the Eastern United States. Beginning in December 1977 and lasting until March, it produced one of the coldest winters on record in all states east of the Rocky Mountains, except Maine.
The climate of Delhi is an overlap between monsoon-influenced humid subtropical and semi-arid, with high variation between summer and winter temperatures and precipitation. Delhi's version of a humid subtropical climate is markedly different from many other humid subtropical cities such as São Paulo, New Orleans and Brisbane in that the city features dust storms and wildfire haze due to its semi-arid climate.
The climate of Allentown, Pennsylvania is classified as a humid continental climate. Allentown's warmest month is July with a daily average temperature of 73.4 °F (23.0 °C) and the coldest month being January with a daily average of 27.8 °F (−2.3 °C). The average precipitation of Allentown is 45.35 inches (1,152 mm) per year.
The January 1987 snowfall was a very heavy lake-effect type snow event that affected the United Kingdom, mainly the areas of East Anglia, South-East England and London between 11 and 14 January and was the heaviest snowfall to fall in that part of the United Kingdom since the winter of 1981/82. Over 50 centimetres (20 in) of snow fell in South East England, with some locations reporting snowfall at 75 centimetres (30 in). Ireland was also affected by the cold wave, reporting more than 10 centimetres (3.9 in) in some areas.
The winter of 2010–2011 in Europe began with an unusually cold November caused by a cold weather cycle that started in southern Scandinavia and subsequently moved south and west over both Belgium and the Netherlands on 25 November and into the west of Scotland and north east England on 26 November. This was due to a low pressure zone in the Baltics, with a high pressure over Greenland on 24 November, and ended in 3 May 2011 in Poland.
The winter of 2010–11 was a weather event that brought heavy snowfalls, record low temperatures, travel chaos and school disruption to the islands of Great Britain and Ireland. It included the United Kingdom's coldest December since Met Office records began, with a mean temperature of −1 °C (30 °F), breaking the previous record of 0.1 °C (32.2 °F) in December 1981. It was also the second coldest December in the narrower Central England Temperature (CET) record series which began in 1659, falling 0.1 °C short of the all-time record set in 1890. Although there are no xx, December 2010 is thought to be colder than December 1890 over the United Kingdom as a whole, as Scotland was up to 2 °C warmer than England. Hence, it is thought to be the coldest December across Great Britain since before 1659.
A deadly cold wave started in Europe on January 27, 2012, and brought snow and freezing temperatures to much of the continent. There were more than 824 reported deaths in both Europe and North Africa. Particularly low temperatures hit several Eastern and Northern European countries, reaching as low as −42.7 °C (−44.9 °F) in Finland. The heaviest snow was recorded in the Balkan region. The cold weather was a result of an extensive area of very high pressure located over the north east of the continent in northern Russia, which circulated cold air from the east.
The cold wave of January 1977 produced the only known trace of snow in the greater Miami area of Florida ever reported. It occurred following the passage of a strong cold front, in combination with a high-pressure area situated over the Mississippi River Valley. As a result, cold air moved far to the south across Florida, causing both snow flurries and record low temperatures. Most notably, the weather system brought snow flurries as far south as Homestead on January 19. No snow had ever been reported in southeastern Florida before or since. Damage was most significant to agriculture, as major losses occurred to citrus fruits and tender vegetables. Statewide, agricultural damage from the cold wave totaled to $350 million (1977 USD), and losses overall totaled to $2 billion (1977 USD). One fatality occurred due to an automobile accident in Central Florida, which was related to the cold wave.
The 1994 North American cold wave occurred over the midwestern and eastern regions of the United States and southern Canada in January 1994, which caused over 100 deaths in the United States alone. Two notable cold air events took place from January 18–19 and January 21–22. There were 67 minimum temperature records set on January 19. Indiana and Kentucky both set state records on January 19. During this time, the United States experienced its coldest temperatures since February 1934, although much of the West experienced mild temperatures. While Washington and Idaho experienced the second-warmest January recorded in the previous 100 years, the eastern United States experienced a major snowfall, which significantly delayed traffic.
The early 2014 North American cold wave was an extreme weather event that extended through the late winter months of the 2013–2014 winter season, and was also part of an unusually cold winter affecting parts of Canada and parts of the north-central and northeastern United States. The event occurred in early 2014 and was caused by a southward shift of the North Polar Vortex. Record-low temperatures also extended well into March.
The November 2014 North American cold wave was an extreme weather event that occurred across most of Canada and the contiguous United States, including parts of the Western United States up to western California. One of the first events of the winter, the cold wave was caused by the northward movement of an extremely powerful bomb cyclone associated with Typhoon Nuri's remnant, which shifted the jet stream far northward, creating an omega block pattern. This allowed a piece of the polar vortex to advance southward into the Central and Eastern United States, bringing record-cold temperatures to much of the region. In contrast, Alaska experienced above-average temperatures.
The 2014–15 North American winter was frigid and prolifically wintry, especially across the eastern half of North America in the months of January–March. The season began early, with many places in North America experiencing their first wintry weather during mid-November. A period of below-average temperatures affected much of the contiguous United States, and several records were broken. An early trace of snowfall was recorded in Arkansas. There were greater accumulations of snow across parts of Oklahoma as well. A quasi-permanent phenomenon referred to as the polar vortex may have been partly responsible for the cold weather. Temperatures in much of the United States dropped 15 to 35 °F below average by November 19, following a southward "dip" of the polar vortex into the eastern two-thirds of the country. The effects of this dip were widespread, bringing about temperatures as low as 28 °F (−2 °C) in Pensacola, Florida. Following a significant snowstorm there, Buffalo, New York received several feet of snow from November 17–21. In addition, significant winter weather occurred throughout the season, including a major blizzard that struck the Northeastern United States at the end of January, another blizzard that affected much of the Northern United States days later in early February, and several significant snow events paired with very frigid temperatures for much of February.
Sweden had a very unusual start and finish to the year 2010, with two consecutive winter cold waves occurring in a single calendar year. Since both events were notable, both are covered in this article.
A period of exceptionally cold and snowy winter weather in January 2017 occurred in Eastern and Central Europe. In some areas, flights and shipping services were suspended, and there was major disruption to power supplies and other essential infrastructure. The weather was the result of stationary high pressure over western Europe, resulting in strong winds circulating from Russia and Scandinavia towards eastern Europe. On 9 January, the Continental Arctic (cA) air mass extended from Germany across the Balkans, resulting in deep snow in Greece and strong bora winds affecting Croatia in particular. In addition, heavy snow in central and Southern Italy was the result of cold air flowing across the warmer Adriatic Sea. At least 73 deaths were attributed to the cold wave.
The February 2015 North American cold wave was an extreme weather event that affected most of Canada and the eastern half of the United States. Following an earlier cold wave in the winter, the period of below-average temperatures contributed to an already unusually cold winter for the Eastern U.S. Several places broke their records for their coldest February on record, while some areas came very close. The cause of the cold wave was due to the polar vortex advancing southward into the eastern parts of the U.S, and even making it as far south as the Southeast, where large snow falls are rare. By the beginning of March, although the pattern did continue for the first week, it abated and retreated near the official end of the winter.
The 2017–18 North American winter saw weather patterns across North America that were very active, erratic, and protracted, especially near the end of the season, resulting in widespread snow and cold across the continent during the winter. Significant events included rare snowfall in the South, an outbreak of frigid temperatures that affected the United States during the final week of 2017 and early weeks of January, and a series of strong nor'easters that affected the Northeastern United States during the month of March. In addition, flooding also took place during the month of February in the Central United States. Finally the winter came to a conclusion with a powerful storm system that caused a tornado outbreak and blizzard in mid-April. The most intense event, however, was an extremely powerful cyclonic blizzard that impacted the Northeastern United States in the first week of 2018. Similar to the previous winter, a La Niña was expected to influence the winter weather across North America.
The Spring 2013 United Kingdom cold wave was a period of unusually cold weather in the United Kingdom between 6 March and early April 2013. The cold wave consisted of very low temperatures and significant snowfall. Freezing temperatures worsened due to the significant overcast and cloud covered skies. Extensive snowfall occurred on 11 and 12 March in the South East, North and West of England and Wales. Most parts of England, north Wales and the Isle of Man also suffered heavy persistent snowfall on 22 and 23 March 2013.