In late January 2019, a severe cold wave caused by a weakened jet stream around the Arctic polar vortex hit the Midwestern United States and Eastern Canada, killing at least 22 people. It came after a winter storm brought up to of snow in some regions from January 27–29, and brought the lowest temperatures in over 20 years to most locations in the affected region, including some all-time record lows. In early February, a concentration of Arctic air colloquially referred to as the "polar vortex" moved west,Edmonton feels the cold as polar vortex makes its way west Edmonton Journal, February 2, 2019 and became locked over Western Canada and the Western United States. As a result, February 2019 was among the coldest and snowiest on record in these regions. In early March, the cold once again shifted east, breaking records in many areas. In mid-March, the cold wave finally retreated, but combined with above-average temperatures, precipitation, and a deep snowpack, widespread flooding ensued in the Central US.

Meteorology

Normally, the Northern Hemisphere jet stream travels fast enough to keep the concentration of Arctic air known as the "polar vortex" stationary in the stratosphere over the North Pole. From late December to early January, a sudden stratospheric warming event was observed over the Arctic, which caused the "polar vortex" to weaken and split into three lobes. In late January 2019, one of these lobes traveled southward and stalled over central Canada and north-central United States for about a week before the upper-level flow of the atmosphere directed it over to Western Canada. The influx of frigid air from the North Pole created high winds, and brought extreme sub-zero temperatures, further exacerbated by severe wind chill. Large amounts of snow fell in the affected area. Some have attributed the unusual weather pattern to climate change.

Impact At least 22 deaths in North America have been directly attributed to the cold wave, with several of these people frozen to death (hypothermia).

Around 2,700 flights were canceled on January 30, with 2,000 canceled the next day. Amtrak also canceled several trains.Polar vortex 2019: Relief coming for the Midwest that is suffering another record-low day NBC News, January 31, 2019

Canada The "polar vortex" split into three parts, with the dominant part setting up over the Great Lakes and Nunavut. This gave prairie Canada and northern Ontario a persistent northern flow, leading to record cold temperatures.

Alberta On February 3, Calgary recorded a temperature of and a wind chill of . On February 5, the city dropped to and a wind chill of . The coldest was actually that was located in Red Deer.

On February 5, Edmonton recorded a temperature of and a wind chill of , as a result of the "polar vortex" making its way west.

Extreme cold carried into March, with temperatures hitting in Calgary on the second, and in Lethbridge, the coldest March temperature ever recorded in the city. Temperatures dropped to in Medicine Hat, only 0.9 away from the March record low.

British Columbia On February 4, the temperature in Richmond dropped to with a wind chill of .

On the same day, the temperature in Abbotsford dropped to with a wind chill of .

Again on the same day, the daily high in downtown Victoria was at , the first time the daily high was below freezing since January 2017. The next day, on February 5, the city's temperature dropped to with a wind chill of .

Prince George dropped to as low as with a wind chill of on February 4. On February 11 the city recorded a temperature of with a wind chill of .

Vancouver recorded a temperature of on February 5. On February 11 the city surpassed this, dropping to . Vancouver had its coldest February on record. One benefit from the cold, however, was that it killed many Japanese beetles, an invasive species to the area.

On February 5, Kelowna dropped to with a wind chill of . The next day, on February 6, the wind chill dropped to as low as . On February 10 the temperature in the city dropped to with a wind chill of .

Temperatures reached in Ashcroft on February 5, the coldest temperature recorded in February since record keeping began in 2010. This record was broken again on the 10th when it reached .

On February 6, the temperature in Nanaimo dropped to and a wind chill of .

Manitoba In Winnipeg, Manitoba, temperatures reached as low as , the coldest temperature recorded in the city since February 2007, when it reached .

Northwest Territories On February 2, the temperature in Yellowknife dropped to and a wind chill of .

Nunavut Environment Canada issued extreme cold warnings for most of Nunavut. The temperature in Baker Lake dropped to a frigid with a wind chill of , its lowest recorded wind chill on record. On January 25, Shepherd Bay recorded .

Ontario

Ottawa experienced its snowiest January on record with temperatures as low as . Toronto experienced the largest snowstorm in six years with of snow accumulating at Toronto Pearson International Airport, before dropping to a low of , with a wind chill of . Many local schools and universities cancelled classes due to the weather. At Niagara Falls, the falls were left partially frozen by the extreme temperatures.

On January 31, Windsor reached with a wind chill of . Warming centres were set up in Windsor and Chatham-Kent libraries for homeless people and anyone else affected by the cold. On the same day, London dropped to with a wind chill of . Temperatures in St. Catharines dropped to . with a wind chill of , while Port Colborne fell to with a wind chill of .

Quebec

The cold snap in Montreal began with a blizzard where base temperatures reached . The combination with a single-day snowfall was the coldest snowiest day in nearly a century. The Fête des neiges winter festival was cancelled due to the extreme cold for the first time in a decade.

Among those killed by the cold was Hélène Rowley Hotte, the 93-year-old mother of Gilles Duceppe, a former federal opposition leader. She was found outside her seniors' residence after being accidentally locked out following a fire alarm.

Saskatchewan In Saskatoon temperatures plummeted to as low as with a frigid wind chill of on February 6.

On February 8, temperatures dropped to and a wind chill of in Regina.

The cold continued throughout the rest of February, resulting in one of the coldest Februaries on record there.

United States California On February 4, the temperature in Eureka dropped to , and the city experienced the coldest February 4 in 30 years. On February 5, the temperature dropped to , also the coldest recorded for that date for 30 years. On February 6, the minimum was , the coldest temperature recorded for that date since 2005. In Humboldt County, snow fell on the beaches for the first time in 16 years.Snow falls at sea level in Northern California, beaches in Humboldt Co. dusted in powder, SFGate, February 4, 2019

On February 4, 2019, in the Bay Area there was of snow, with a temperature of . Around the Sierra Nevada Mountain range the temperature there was and of snow fell between February 4 and February 16. This year had the most significant snowfall in California since 2011.

In Downtown Los Angeles, the temperature never reached the entire month of February, the first ever occurrence in 142 years of record-keeping. On February 22, snow was reported in the lower elevations West Hollywood, Eagle Rock and Pasadena within the urban areas of Los Angeles.

Across the state, the persistent cold and heavy rains were beneficial in eliminating drought conditions in California for the first time since 2011.

District of Columbia In the early morning of January 31, 2019, Washington, D.C., as measured at Ronald Reagan Washington National Airport, reached .Streit, David (January 31, 2019). "D.C.-area forecast: Bitter arctic air today with snow showers possible tomorrow". The Washington Post. The wind chill reached . Nearby Washington Dulles International Airport reached an air temperature of , the coldest reading since another cold spell in February 2015.

Illinois

In the Chicago area, temperatures plummeted as low as at O'Hare International Airport on January 30, with a windchill of . Chicago's Northerly Island recorded temperatures as low as and Chicago's Midway International Airport recorded a temperature of ; O'Hare's maximum of that day was a daily record and also only higher than Chicago's official record cold maximum set on January 18, 1994, and December 24, 1983. Chicago also reached record lows on January 31, with a temperature of and a windchill of .

Rockford reached an all-time record low of , shattering the old record of from 1982. Moline in the Quad Cities reached an all-time record low of . In Mount Carroll, a temperature of was recorded on January 30. Now verified, this is the all-time lowest temperature in the state of Illinois.

Several people died in Chicago due to the cold. The cold wave resulted in 1,444 flights being cancelled at O'Hare, and 254 flights being cancelled at Midway.More Than 1,600 Flights Canceled at Chicago Airports As Dangerous Cold Continues, NBC Chicago, January 31, 2019

Indiana Temperatures in Indianapolis plummeted as low as on January 30, tying the record low, with a wind chill of . Kokomo recorded a wind chill of while Evansville recorded wind chills as low as .

Hundreds of schools and businesses closed and the United States Postal Service suspended delivery service on Wednesday, January 30 and Thursday, January 31.

Temperatures in South Bend plummeted as low as , and all classes at the University of Notre Dame were cancelled. Other major universities in the state, such as Indiana University, Purdue University and Ball State University, also cancelled all classes.

Iowa Temperatures broke records, with the coldest temperature ever recorded at on January 31, 2019. Wind chills got dangerously low as on January 30, 2019. Most universities closed, including Iowa State University, University of Northern Iowa, and the University of Iowa. University of Iowa student Gerald Belz died after being found unresponsive near Halsey Hall.

Kentucky After windchill temperatures were predicted to plunge to between to , many Kentucky schools closed.

Two brothers in Boone County, Obie (72) and Roy Fugate (67), died in their driveway outside of their home due to the cold after their truck was stuck in the mud.

Michigan On January 28, Michigan Governor Gretchen Whitmer declared a state of emergency due to the record low windchill temperatures.Gov. Whitmer declares state of emergency in Michigan WILX, January 28, 2019 Three people died due to the extremely low temperatures in Michigan: one in Detroit, another in Ecorse, and a third in East Lansing.East Lansing man found dead outdoors in extreme cold WNEM-TV, January 31, 2019

On January 31, the city of Flint recorded a low temperature of , breaking the record for that date of , set in 1963. The previous day's maximum temperature of broke the record cold maximum of set in 1951.Flint breaks cold weather record set in 1963 The Flint Journal via MLive.com, January 31, 2019 In Metro Detroit on January 31, temperatures were between to with windchill values between and .Dangerous cold continues in Metro Detroit: Wind chills at −30 degrees and below WDIV, January 31, 2019 The community named Hell in Livingston County was declared to be frozen over on January 31.Hell (MI) has frozen over WNEM-TV, January 31, 2019

Whitmer and Consumers Energy asked residents to turn down their thermostats to until midnight ET on February 1, after a fire at the compressor station in Macomb County on January 30 due to extra gas usage during the cold wave, to avoid "heat interruptions".You can turn your heat back up after midnight, Consumers Energy says MLive.com, January 31, 2019Consumers Energy apologizes for equipment failure, thanks residents for turning down heat WEYI-TV, January 31, 2019