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)
Strong southerly winds brought very warm air from the Gulf region into Illinois. Rockford reached 91 degrees, which stands as the city's October warmest temperature. The heat wave across the region persisted through the 5th.