Winds will gradually shift to the south Thursday, bringing temperatures to at least the normal upper 40s and lower 50s , in direct contrast to Wednesday, when a brisk northeast breeze off the 30-degree waters of Lake Michigan augmented an already cold high pressure air mass, keeping readings in the 30s.

The big change will occur Friday as winds strengthen from the south-southwest, pushing much warmer air into northeast Illinois and northwest Indiana. Temperatures should warm into the upper 60s and 70s, depending on increasing cloudiness. Friday night a frontal boundary may bisect the area. Amid occasional showers and thunderstorms, northeast winds behind the front will keep readings in the 40s, while south of the front southerly winds will allow temperatures to reach into the 60s.