PROGRAMMING NOTE: 4PM White Sox Game preempts our WGN Evening News

Which month features the largest spread in high, low temperatures?

Dear Tom,
Comparing Chicago record high and low temperatures, which month features the largest spread? March seems like a good bet.
— Tom Gregg, Niles

Dear Tom,
March it is. March leads all other months with an incredible 100-degree span between its highest and lowest temperatures, from 88 on March 29, 1986, to 12 below zero on March 4, 1873. Runner-up months are February and December, each with a 96-degree spread between extremes.

Chicago experiences a continental climate, the main characteristic of which is large, abrupt and frequent temperature fluctuations. While wide-ranging extremes most often occur in winter and spring, September is no stranger to huge temperature shifts. It’s been as hot as 101 degrees on Sept. 1 and 2, 1953, and as cold as 29 on Sept. 28, 1942; Sept. 30, 1984; and Sept 23, 1995, a range of 72 degrees