Thunderstorms arrive in the area Friday night before cooler temps Saturday

Thunderstorms hit the area Friday night before cooler temperatures were expected for the weekend.

A tornado watch was in effect for 11 counties in Illinois until Friday at 11 p.m. Those counties iincluded: Cook, DuPage, Grundy, Kane, Kankakee, Kendall Lake, Will Livingston, Ford and Iroquois. A tornado warning was issued late Friday for the Kankakee area.

The National Weather Service cautions residents to "remain alert" amid the tornado watch. Tornadoes may develop rapidly from severe thunderstorms. If a tornado is spotted, residents are urged to go to a basement or a small central room in a sturdy structure, according to the weather service.

By Saturday, the high is expected be 30 degrees cooler than Friday's 80s, and by Saturday night temperatures could hover just above the freezing point, according to the weather service. A slight chance of rain is possible, and wind gusts are expected to reach 30 mph.

Conditions are expected to be calm Sunday and Monday, and highs in the 70s are expected to return by Tuesday.