Arctic Cold Wave Hits United States

In January 2019, a severe cold wave caused by the Arctic polar vortex hit the Midwestern United States and Eastern Canada, killing at least 21 people. It came after a winter storm brought up to 13 inches (33 cm) of snow in some regions from January 27–29.

Normally, the Northern Hemisphere jet stream travels fast enough to keep the polar vortex stationary in the stratosphere over the North Pole. In late January 2019, a weakening of the jet stream split the polar vortex in two, with one formation traveling southward and stalling over central Canada and north-central United States for about a week before it dissipated. 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.

In the Chicago area, temperatures plummeted as low as −23 °F (−31 °C) at O'Hare International Airport on January 30, with a windchill of −52 °F (−47 °C). Chicago's Northerly Island recorded temperatures as low as −21 °F (−29 °C) and Chicago's Midway International Airport recorded a temperature of −22 °F (−30 °C).[6] Chicago also reached record lows on January 31, with a temperature of −21 °F (−29 °C) and a windchill of −41 °F (−41 °C). Rockford reached an all-time record low of −31 °F (−35 °C), shattering the old record of −27 °F (−33 °C) from 1982. Moline in the Quad Cities reached an all-time record low of −33 °F (−36 °C). In Mount Carroll, a temperature of −38 °F (−39 °C) was recorded on January 30. If verified, this would be the all-time lowest temperature in the state of Illinois.