All this heat and humidity is wearing me down. When can we expect our first sub-60 high, or better yet, two in a row?
It will likely be a while. Chicago typically does not record its first end-of-the warm-season sub-60 high until late September, with the average date of the first occurrence on September 27. Since 1871, there has only been one such occurrence in August, a chilly high of 58 on August 30, 1915. Since 2015, the season’s first high in the 50s has occurred in October and the city’s very-latest on record was in 1963 with a high of 57 on October 29. Extended strings of sub-60 days do occur in September, most recently three in a row (56º,55º,59º) from September 11-13, 2014. The city’s longest September sub-60 run was six days (55º,56º,57º,53º,51º,58º) from September 17-22, 1875.