CHICAGO (CBS) -- There is a large temperature spread on either side of the warm front, which continues to drift northward through northern Illinois.

It's cool in 40s and 50s along the North Shore with fog, but warmer south of Interstate 80, according to CBS 2 Meteorologist Mary Kay Kleist. 

Where the warm air resides, mainly south of the Kankakee River Valley and into Newton and Jasper counties, we could end up with thunderstorms this afternoon.

The area dries out tonight and sun returns by Tuesday afternoon.

TONIGHT: EVENING SHOWERS TAPER OFF. PATCHY FOG. LOW 49.

TUESDAY: AM CLOUDS. PM SUN. HIGH 70.

WEDNESDAY: SUNNY. HIGH 75.