In a recent column, you stated that the city’s record greatest daily temperature range was in March. Looking at the average daily temperature range by month, are there significant differences?
Thanks, Jay Wait Shorewood
There are. Persistent cloudiness tends to keep the temperature range smaller in the winter months, while clearer skies in the warmer months, over the long run, result in warmer days and larger ranges. Chicago’s monthly average temperature range is greatest in May at 21.7 degrees, based on the month’s average high of 70.0 and a low of 48.3 The smallest range of 14.1 degrees occurs in December, with an average high of 34.8 and low of 20.7. The ranges in the other ten months, in descending order, are June 21.6 degrees, September 20.5, April and July 20.2, October 19.5, August 19.0, March 17.4, November 15.8, February 15.2, and January 14.5.