page_title: 2017–18 North American winter
hierarchical_section_title: 2017–18 North American winter
caption_attribution_description: English: Much like last February, unseasonable warmth spread across the southern and eastern United States this week, with temperatures reaching levels more typical of April or early May. This map shows maximum surface temperatures (at 2 meters) across the United States on Wednesday, February 21, 2018, using data from NOAA's Real-Time Mesoscale Analysis. While the western U.S. has been colder than average, temperatures climbed as high as the lower 80s (°F) across the South and the Mid-Atlantic, with 70-degree temperatures reaching as far north as northern New England. Several cities set new records for their warmest February temperatures ever recorded. Pittsburgh, Pennsylvania and Cincinnati, Ohio reached 78 and 79 degrees (°F), respectively, on February 20, while the temperature in New York City soared to 78 degrees on February 21, the National Weather Service reported. Boston, Massachusetts warmed to 72°F on February 21, one degree shy of its all-time February temperature record set just last year. On average, Boston's first 70-degree day typically does not occur until mid-April. Caption credit: NOAA
context_page_description: The 2017–18 North American winter refers to winter in North America as it occurred across the continent from late 2017 through early 2018. Similar to the previous winter, a La Niña was expected to influence the winter weather across North America. Winter weather patterns were very active, erratic, and protracted, especially near the end of the season. Significant events included rare snowfall in the South, a strong cold wave that affected the United States during the early weeks of January, and a series of strong nor'easters that affected the Northeastern U.S 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 flooding 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.
  While there is no well-agreed-upon date used to indicate the start of winter in the Northern Hemisphere, there are two definitions of winter which may be used.
context_section_description: The 2017–18 North American winter refers to winter in North America as it occurred across the continent from late 2017 through early 2018. Similar to the previous winter, a La Niña was expected to influence the winter weather across North America.  Winter weather patterns were very active, erratic, and protracted, especially near the end of the season. Significant events included rare snowfall in the South, a strong cold wave that affected the United States during the early weeks of January, and a series of strong nor'easters that affected the Northeastern U.S 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 flooding 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.
  While there is no well-agreed-upon date used to indicate the start of winter in the Northern Hemisphere, there are two definitions of winter which may be used. Based on the astronomical definition, winter began at the winter solstice, which in 2017 occurred on December 21, and ends at the March equinox, which in 2018 occurred on March 20. Based on the meteorological definition, the first day of winter is December 1 and the last day February 28. Each definition involves a period of approximately three months, with some variability with both definitions containing two months and a week. Winter is often defined by meteorologists to be the three calendar months with the lowest average temperatures. Since both definitions span the calendar year, it is possible to have a winter storm in two different years.
caption: A temperature map of the variable conditions in Central North America on February 21, 2018
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