The 1994 North American cold wave occurred over the midwestern United States, eastern United States, and southern Canada during January 1994. Two notable cold air events occurred from January 18-19 and from January 21-22. There were 67 minimum temperature records set on January 19.Indiana and Kentucky both set state records on January 19. The United States experienced its coldest temperature month since February 1934, although much of the West experienced mild temperatures. Washington and Idaho experienced the second-warmest January recorded in the previous 100 years.
During the same period, the western United States experienced one of its most damaging earthquakes ever, and the eastern United States experienced a major snowfall that significantly delayed traffic.
Over 100 deaths occurred in the United States as a result of the cold wave.
Cold air outbreaks are characterized by strong upper-level troughs in the atmosphere, with ridges usually located up and downstream. On January 17, the 500 millibar (mb) height contours showed the low-pressure center situated near the border of Ontario and Manitoba, just north of Minnesota, with the trough axis stretching down into the Upper Midwest. The 500 mb height contours on January 18, 1994, showed the strong trough over the Great Lakes region extending southward that brought cold air down from the North Pole. MERRA-2 reanalysis detailed the cold air funneling into the Upper Midwest from Canada on January 18, with strong winds out of the northwest. The surface analysis map on January 18 showed a low-level ridge over the Upper Midwest and surface winds blowing out of the northwest. The surface anticyclones on January 18 and 21 both exceeded 1040 mb and moved to the southeast, bringing cold air to much of the eastern half of the United States. By January 19, the upper levels showed a retreat of the low-pressure center, however, shortwave troughs were still located near the United States, and surface temperature effects with the strong anticyclone were felt for days to come.
While the cold air was the dominant story, snow was still associated with this cold weather outbreak. From January 17-18, a snowstorm affected areas from the Ozarks to New England. Ice affected much of the Mid-Atlantic region. A new single-storm record was broken in Louisville, Kentucky with 16 inches of snowfall recorded, while accumulations of sleet and freezing rain in New York City were in excess of an inch.
On January 19, the temperature in New Whiteland, Indiana dropped to -36 °F (-37.8 °C), the record-lowest temperature in Indiana. The minimum record temperature in Kentucky was -37 °F (-38.3 °C) in Shelbyville on January 19, 1994.
Pittsburgh, Pennsylvania saw its record-low temperature of -22 °F (-30 °C) on January 19, 1994.Columbus, Ohio set an all-time record-low temperature of -22 °F (-30 °C) on January 19 as well. However, the arctic blast lasted for three days from January 18 to 20.
Maine had its coldest month since February 1934 and its coldest January since 1920, while Vermont had its coldest winter since 1958-1959 and the adjacent states of New Hampshire and Maine their coldest since 1976-1977 or 1970-1971.
January was also a month of extremes in Canada. Temperatures in the Yukon got close to -50 °C (-58 °F). In Yellowknife, the temperature did not go higher than -40 °C (-40 °F) for many days. In Windsor, Ontario, the coldest temperature since 1885 was recorded on January 19 of -29 °C (-20 °F). The cold air was also accompanied by large snowfalls, with 50 centimeters (20 inches) falling on the western side of Lake Ontario. Just like the mild pattern in the western United States, southern British Columbia got above 10 °C (50 °F) several times during the month of January. Rapid melting and freezing near the end of the January closed Toronto Pearson International Airport on January 30 for the first time in 60 years. Water shortages were also common in Goose Bay due to the extreme temperatures.
Minneapolis-Saint Paul is one of the areas that felt major impacts from the cold wave. From 3 PM CST on January 13 to 1 PM CST on January 19, the temperature recorded at Minneapolis-Saint Paul International Airport stayed at or below zero, marking 142 continuous hours. This was the sixth-longest stretch on record from 1873-2014. Governor Arne Carlson closed all public schools in Minnesota on January 18, with wind chills of -48 °F (-44 °C) and morning air temperatures of -26 °F (-32 °C).
Temperatures in Chicago, Illinois reached -21 °F (-29.4 °C) with wind chills of -55 °F (-48.3 °C), the coldest day of the 1990s in Chicago. Almost all primary and secondary schools in Chicago were closed that day. Richard Daley, mayor of Chicago advised residents not to go outside if they do not have to. Nearly all schools in the area were closed and four people in Cook County, Illinois died from hypothermia. Hundreds of drivers per hour complained to the AAA-Chicago Motor Club about dead automobile batteries, fuel injectors being too cold and other vehicle issues and United Airlines canceled almost half of its flights. Tens of thousands of individuals complained about a lack of power due to severed electricity lines while water companies shut off water to homes as a result of pipe explosions. Thousands of apartment renters complained to Cook County about insufficient heat.