Has the Chicago area seen an actual decline in the average number of days with rain over the past 30 years? It sure seems like it.
—John Holden, Chicago, Edgewater
It has not. Checking city’s entire precipitation climatology, which dates back to 1871, the city has averaged 125 days a year with measurable precipitation (at least 0.01″ ). During that 150-year span, the number of measurable precipitation days has ranged from a maximum of 166 in 1878 to a minimum of 96 in 1963. We asked Chicago climatologist Frank Wachowski to check the number of days in the past 30 years, and he found the average to be a similar 126 days. The years 2019 and 2018 logged the most days with measurable precipitation with 151 and 147 respectively, while 2004 with 107, and 2002 and 2012 with 109 had the fewest.