It seems that we had a lot of record low temperatures set in the 1980s. Is that true?
It is indeed true. The explanation is twofold. The actual weather, of course, is an important factor, and intense cold spells characterized several of Chicago’s winters during the 1980s, but a major predominating influence was change in the site of the city’s official weather observations. After several locations well within the city since 1870, the official site was moved to O’Hare International Airport on Jan. 17, 1980, a more rural location removed from the metropolitan heat island. That site typically registers lower temperatures, especially during the summer. On average, Chicago ties or establishes four daily record low temperature per year, but during the 1980s the average was 10 per year.