Chicago’s greatest calendar-day temperature variation

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Dear Tom,
Can Frank Wachowski provide this information? What is Chicago’s greatest temperature variation measured on a particular calendar day from one year to the next?
—Michael Michelotti, St. Charles
Dear Michael,
He sure can. Huge temperature variations are part of our meteorological DNA. The Christmas periods in 1982 and 1983 could not have been more different and set the bar for same-day temperature changes in consecutive years. In 1982, driven by a strong El Nino, temperatures soared into the 60s, while in 1983, a roaring Siberian Express sent the mercury plunging far below zero. Wachowski noted that the 83-degree span between the 62-degree high and the low of minus 21 on December 21 is the greatest, closely followed by an 81 degree difference on Christmas Day ranging from a high of 64 to a low of minus 17.