Climatologists are not only worried about increased high temperatures, but also the increasing number of high nighttime temperatures that do not allow living organisms to recover from excessive daytime heat. What is the difference between Chicago’s summer minimum temperatures in 2001 compared to 2021?
—Kathy Schreiner, Naperville
Chicago’s summer minimum temperatures are going up, and some of it can be attributed to this area’s increasing urbanization. Chicago’s summer minimums in 2001 averaged 61.7 degrees, compared to 64.1 this past summer. Days with 70-plus lows increased from just 13 in 2001 to 36 in 2021. The change in the summer minimum temperature based on 30-year normals is just as revealing, increasing from 61.7 in the 1981-2010 period to 64.1 for the current 1991-2020 normal period.