Dear Tom,
What is Chicago’s longest spell of absolutely dry weather?
— Blake Jeffreys, Chicago
Dear Blake,
The Chicago record for no precipitation is 22 days, from Sept. 2-23, 1979. One-hundredth of an inch of rain fell Sept. 1 and a trace on Sept. 24. Another trace of rain occurred Sept. 30, making the month’s total precipitation a meager 0.01 inch. September 1979 stands as the driest month in Chicago weather history. In 1979, Aug. 30 and 31 were dry, but 0.67 inches fell on Aug. 29. In October, 0.69 inches fell on Oct. 1. Chicago’s longest stretch of days with no measurable precipitation (0.00 inches or traces) occurred Jan. 7 through Feb. 5, 1919 — 30 consecutive days. Eight days had traces and 22 days registered no precipitation. Jan. 6 registered 0.10 inches (as snow) and Feb. 6 had 0.01 inches (snow).
