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Dear Tom,

What is the lowest wind chill ever recorded in Chicago?

—Guillermo Costales Chicago

Dear Guillermo,

During the late 1970s and early 1980s, Chicago experienced some of its worst winters on record with many episodes of heavy snow and intense cold. On a horribly- frigid Christmas Eve in 1983, the city’s temperature dropped to -23 combined with a 29 mph wind producing a windchill of minus 82. That minus 82 windchill is the lowest ever recorded in Chicago and is one weather record that will probably never be broken. In 2001, a more realistic windchill formula was implemented and the same conditions on that 1983 Christmas Eve would now produce a windchill value of only minus 57. The new formula would require a temperature of minus 41 combined with a sustained 30 mph wind to equal that minus 82 value.