Chicago's south suburbs and northwest Indiana are under a Level 2 risk, while much of the rest of the area is under a Level 1 risk.
There is a 2% risk of tornadoes in the south suburbs and a 5% risk of tornadoes in northwest Indiana.
Scattered showers and isolated thunderstorms are expected from 4 to 9 a.m.
Between noon and 5 p.m., more isolated thunderstorms are possible. Those storms have the chance to become severe.
The main threat would be large hail and high winds with any storm.
Two weeks after tornadoes tore through the area, parts of northwest Indiana are expected to have their power restored Tuesday.