The statewide average temperature in Illinois was 63.2 degrees, 3 degrees below average, and the 13th coolest September on record for the state. The coolest September was in 1918 with 59.3 degrees, according to State Climatologist Jim Angel at the Illinois State Water Survey.
The coldest spot for the month was Paw Paw with 32 degrees on Sepember 15. Also on that day, the temperature at Stockton and Marengo dipped down to 34 degrees. Twenty-two weather stations either set or broke daily records for low temperatures.
Although September was a cool month on average, it began with a burst of heat on Labor Day weekend. Highs reached the upper 90s and 100s. The highest temperature was recorded at Quincy with 104 degrees on September 1. Jacksonville reached 103 degrees on September 2.
In all, at least 65 weather stations in Illinois either tied or broke daily records for high temperatures in early September.
Precipitation was normal for the month. The average precipitation in September was 3.53 inches, 0.34 inches above average. Rainfall was stubbornly sparse in the areas hardest hit by drought where only 1 to 2 inches were common. Amounts in far southern and northern Illinois were much wetter at 4 to 8 inches.