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The Average Rainfall in Chicago

Weather records in the Chicago area date to the late nineteenth century. The best-known recording station for the city is the official site at O'Hare International Airport, where recording began in 1959. Records at the city's other major airfield, Midway Airport, extend to 1928.

Monthly Precipitation
- Chicago's average monthly precipitation ranges from a low of 1.63 inches in February to a high of 4.62 inches in August. January is also dry, with an average of 1.75 inches. April is a distant second for wettest month, with an average of 3.68 inches.
Annual Precipitation
- Chicago's mean annual precipitation is 34.32 inches. The wettest year on record is 2008 at 50.86 inches; the driest, 22.22 inches in 1962.
Rainfall Records
- Chicago's record wettest month was August 1987 (17.10 inches), while September 1979, saw only 0.01 inches. The greatest daily rainfall recorded came on September 13, 2008, at 6.64 inches; a total of 9.35 inches fell in 24 hours on August 13-14, 1987.

Nature