Periods of rain have returned to the Chicago area, with the second round arriving overnight tonight. Waves of rain with occasional thunderstorms are expected to yield rain totals of 0.75"-1" by mid-morning Tuesday.

After a mild and cloudy evening Sunday, the Chicago area is set to experience a week of rapidly changing weather, including rain, cooler temperatures, and even a chance of wet snow.

The Chicago area typically sees its first trace of snow Oct. 31, Roman said. The area's first measurable snow -- 0.1 of an inch or more -- usually comes Nov. 18, Roman said, and the area's first average snow of one inch or more typically occurs Dec. 7.