What is Chicago's record for consecutive days without rain?
A search of Chicago's precipitation records from Nov. 1, 1870, to the present reveals that the city's longest string of consecutive dry days is 30. (That's using the National Weather Service's definition of a "dry day" as a day without measurable precipitation — at least 0.01 inch.)
Chicago's record-long dry spell began Jan. 7, 1919, and continued through Feb. 5. Total precipitation for January 1919 was only 0.20 inch, but the 30-day dry spell had little negative effect because it occurred during the winter when the evaporation rate is low, vegetation is dormant and requires little water, and because moisture in the months before and after was ample: 2.65 inches in November 1918; 3.24 inches in December 1918; 2.78 inches in February 1919; 4.32 inches in March 1919.