All indicators are pointing towards a cool August in Illinois. The statewide temperature for the first 7 days of August has averaged 72.0 degrees, which is about 1.5 degrees below average for the month. The 1981-2010 statewide average temperature for the entire month of August is 73.5 degrees. This follows on the heels of a July that was already two degrees below average.
The forecasts for the next 5 days and beyond (see maps below) point towards a strong chance that August will continue to be below the 1981-2010 average.
It will be hard to beat the five coolest Augusts on record since they are all five to six degrees colder than the 1981-2010 average. Here they are:
- August 1915 with an average temperature of 67.2 degrees
- August 2004 with an average temperature of 68.5 degrees
- August 1992 with an average temperature of 68.5 degrees
- August 1927 with an average temperature of 68.5 degrees (yes, a 3-way tie for second place)
- August 1967 with an average temperature of 68.6 degrees
One footnote: daily August temperatures, on average, cool slightly throughout the month by about two to four degrees, depending on your location. For example, here are the daily August averages for Chicago, Rockford, Peoria, Springfield, and Champaign-Urbana.