CHICAGO — Mostly sunny Friday with a 20% chance of showers and thunderstorms. Winds: SW 5-10 G15. High: 89.

Mostly cloudy tonight with showers and thunderstorms. Winds: SW 5-10 G15. Low: 71.

Saturday Forecast: Partly cloudy, AM and early day thunderstorms, slighter afternoon chance, very hot and humid. Winds: SW 10-15 G20. High: 93. Showers and storms back overnight Saturday into Sunday.