Based on the latest updates from the National Climatic Data Center, this summer in Illinois was the 29th coolest. Daytime highs were much cooler than average while the nighttime lows were near-average.
The average maximum temperature in Illinois was 82.3 degrees Fahrenheit, 2.6 degrees below the 1900-2000 base period and the 14th coolest on record.
The average minimum temperature in Illinois was 62.3 degrees F, 0.3 degrees above the 1900-2000 based period.
In contrast to the cool summer in the central US, most of the globe was warmer than average this summer (June-August), according to the National Climatic Data Center. In fact, even in the US, temperatures were significantly warmer in the West than the East.
Across the globe, there were a few other cool spots including parts of Russia and Australia. Otherwise it was warm. Overall, the global temperature for June-August was 0.71 degrees Celsius (1.28 degrees Fahrenheit) above the 1900-2000 base period, just beating out 1998 to be the warmest June-August on record. Global records for this data set go back to 1880. Source: NCDC Global Analysis page.