A heat advisory in the Chicago area is over, but a new threat of severe weather will arrive in advance of a dramatic drop in temperatures.

"Severe" weather could reportedly strike four U.S. states on Sunday afternoon. The National Weather Service is warning four U.S. states about potentially severe weather on Sunday. Major storms, including heavy thunderstorms,

The most intense storms, with wind gusts potentially exceeding 75 m.p.h., were forecast for central and eastern South Dakota, southwestern Minnesota and northern Iowa.

There is a chance of severe weather across the ABC 6 News area Monday night, with the majority of that threat coming during the overnight hours.