Towards the end of June 2018, Chicago saw 6 inches (15.24 cm) well above the 2-inch (5 cm) historical average, causing sewage discharge into the Chicago River on the city’s Northwest Side.

In July 2018 locally heavy rainfall and thunderstorms caused numerous reports of flooding, mainly across the southern and Indiana suburbs. Rainfall totals in excess of 2.5 inches (6.35 cm) fell causing significant flooding in Lake County, Indiana with Munster, Calumet City and Lynwood especially hardest hit.