Shae Cohan photographed these sprites on August 26. Sprites are electrical discharges that occur above thunderstorms, typically at an altitude of 30 to 55 miles. The picture was taken from Macomb, although the storms in question were southeast of Springfield near Taylorville. (click image to enlarge)
Flash flooding occurred in parts of central Illinois, primarily from near Peoria and Lincoln eastward to Bloomington, as rainfall amounts ranged from 3 to 7 inches. Bloomington reported 7.12 inches between midnight and 4 am, causing significant flooding.
Peoria recorded its earliest freeze on record; the normal first freeze isn't until October 17th. This is also the only time in Peoria's recorded history that a freeze has occurred during astronomical summer.