Dear Tom,
You just mentioned that Chicago’s lowest recorded relative humidity is 13%, but you gave no other information. Could you please amplify with more detail?
Dan Feeney
Dear Dan,
Episodes of low relative humidity–readings of 20% or lower–are very rare in Chicago, having occurred on less than 20 occasions since the inception of the city’s weather records in late 1870.
Those readings occur mainly on windy days in the early spring and late autumn when the temperature can rise to warm levels, but when dormant vegetation adds no moisture to the air. Strong winds mix dry air aloft down to the surface, helping to lower the relative humidity.
Chicago’s lowest, 13%, was registered on three occasions: May 10, 1934; April 11, 1956; April 8, 1971.
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Tom Skilling is chief meteorologist at WGN-TV. His forecasts can be seen Monday through Friday on WGN-TV News at noon and 9 p.m.
WGN-TV meteorologists Steve Kahn, Richard Koeneman and Paul Dailey plus weather producer Bill Snyder contribute to this page.
