The February 2015North Americancold 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 southwards 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. In addition to the extremely cold weather, multiple winter storms affected nearly the entire United States, especially in the snow-weary Northeast, which had already seen nearly of snow in the latter part of January; this was added to by roughly more snow, leading to Boston having its highest seasonal snowfall on record.
Origins
Like most normal cold waves, the cold wave was caused by the southwards movement of the polar vortex into the United States due to changes in the jet stream in early February 2015. However, unlike most which last for a few days, this one remained for much of the entire month. This was partly due to the Ridiculously Resilient Ridge, which persisted over parts of Alaska for much of the month, essentially keeping the jet stream pattern "locked" for several weeks. This allowed for bitterly cold air masses to migrate southwards into the eastern part of the country, leading to well-below average temperatures.
Record temperatures
The average temperature in Boston for January was below the 1981–2010 normal, and the average temperature in February was, which was below the 1981–2010 normal, making it the second-coldest month of any month all-time, behind February 1934. March was below average. By the end of a period spanning from the beginning of February to the end of December, Worcester, Massachusetts, saw a record of snowfall, breaking the record set in 2004–05, which was over the average. Hartford, Connecticut, and Providence, Rhode Island, saw similar below-average temperatures for the two months, with Hartford's February finish of besting February 1934 to become the coldest month of any month all-time in record keeping. The average temperature in Bangor, Maine, for February was, about below normal, breaking the old record of set in January 1994. Portland, Maine, also saw a record coldest average monthly temperature of in February. On February 24, 2015, the temperature at Dulles International Airport in Northern Virginia dipped to, breaking the previous daily record of set in 1967. Rutland, Vermont, saw a record averaged cold for February of, breaking its previous record of set in 1934. Montpelier, Vermont, realized its coldest February with an average temperature of, below the 1979 record of. The average February temperature in Syracuse, New York, was degrees below normal at, breaking by 3 degrees the record set in February 1934. The average temperature in Buffalo, New York, set a record in February for its all-time coldest month with an average temperature of. breaking the prior record set in 1934 of. Before that, the previous coldest February was in 1875 with an average temperature of. It was also the second time in history that the entire month of February was below freezing. Other cities that broke cold weather records for February included Cleveland, at, while Chicago tied its February 1875 record at. Rochester, New York, also set a record for coldest month overall. Ohio experienced the coldest winter since 1977–78 with an average temperature of below normal. Toronto recorded its coldest month on record in February with at Pearson Airport, tying with February 1875 and beating the previous record of set in January 1994. In Quebec, Montreal experienced its coldest February on record with an extended cold spell and an average temperature of.
Related weather
Most of the northern half of the United States and even parts of Canada saw several winter storms impact them; each of them had somewhat unique traits. At the start of the month, a major snowstorm was moving across the country, having previously brought blizzard conditions to the Midwest, especially in Chicago, Illinois, where more than a foot of snow was recorded. This storm continued to dump large amounts of snow as it progressed into the Northeast and New England, before finally exiting offshore. Less than a week later, another winter storm struck New England, with up to nearly of snow recorded in Boston, Massachusetts over a period of two days. This was the beginning of a three-week streak of winter storms that would progress into the Northeast. Around the middle of the month, near Valentine's Day, a powerful blizzard struck the Northeast again, bringing strong winds and more heavy snowfall. Afterwards, as the storm exited, it ushered in the coldest air to impact the Northeast in decades, with temperatures dipping as far as below average. Several places broke record lows for February, and temperatures even dipped below in a good part of the Northeast. Several more winter storms followed afterwards, but one of the more notable ones was the one that occurred from February 25–26. This particular storm took an unusual track into the Southeastern United States as the jet stream along with the polar vortex pushed even further southward, resulting in heavy snowfall in states that rarely see it at all, this included Mississippi, Alabama, Georgia, and the Carolinas. Up to fell in the hardest hit areas, which was in North Carolina and Virginia.
