Has the total annual rainfall amount, on average, dropped over the past 30 years? Are we having the same number of rain days but with less total rainfall?
—Mike Michalides, Elgin
It has not, the annual totals are increasing. Chicago climatologist Frank Wachowski found that over the 150-year course of the city’s precipitation records, annual precipitation has ranged from 22.22 inches in 1961 to 50.86 inches in 2008. During the early years of Chicago’s climate records from 1871-1920, annual precipitation averaged around 33 inches, with a similar total from 1921-1950 when 30-year normals were instituted. For site consistency, Wachowski checked the evolving precipitation normals for Midway Airport starting from 1931 and found a gradual increase from 33.18 inches (1931-1960) to a current peak of 40.88 inches(1991-2020).