What have been the warmest and coolest September’s in Chicago?
September, the first month of meteorological autumn, is typically when the atmosphere begins its annual transition from summer to fall. Chicago climatologist Frank Wachowski found that since 1871, the month’s average temperature has spanned 12 degrees from 71.2 in 1931, the warmest, to 59.2 in 1993, the coolest. September 1991 featured nine days in the 90s, the warmest day, a 94 on September 10. The chilliest day was September 26, with a high of 59, and the month’s lowest reading was 50 degrees on September 28-29. In chilling contrast, September 1993’s highest temperature was just 80 on the 12th, and after the 15th, the month logged only one day in the 70s, a high of 77 on the 22nd. There were three-morning lows in the 30s, including a 31-degree freeze on September 30.