Dear Tom,
Has Chicago's average temperature changed through the years?
John Mannos Chicago
Dear John,
Chicago's long-term climate record that dates back to late 1870 is difficult to analyze
because of the numerous changes in the location of the city's official thermometer.
Through June 1942 readings were taken in an urban environment close to Lake
Michigan. From July, 1942 through mid-January 1980, the readings were logged at
Midway Airport, still an urban environment but not near the lake. Since then the official
site has been at O'Hare International Airport, a more rural, inland location. Despite all
these site variances, there has been little change. The city's earliest average
temperature, from 1871-1910 was 48.8 degrees and the most recent, from 1971-2000
is 49.1 degrees.
