What are the Chicago records for high and low humidity? Has there ever been a summer here that had primarily low humidity?
Tom Downes, Mount Greenwood
It’s an easy task to pinpoint Chicago’s lowest humidity, an arid 12 percent reached at 2 pm on April 20, 2019, with a temperature of 63 and a dew point of 10. High humidity records are meaningless, since the city has recorded 100 percent relative humidity on countless occasions, often for hours on end in dense fog situations. A better way to look at the city’s summer humidity levels would be to focus on the years with the most and least humid days; days with dew points of 70 degrees or higher. Using O’Hare data, dating back to 1959, 2002 was the muggiest year with 51 days of 70-plus dewpoints and 1966 the least with just 14. In a typical summer, Chicago logs 30 days with at least a 70 dew point.