CHICAGO (CBS) — It’s going to be a steamy Sunday with highs in the lower 90s and plenty of sunshine. Hot and humid weather continues through most of the week, and heat index values near 100 degrees by Wednesday.

Sunday brings a slight chance for a hit or miss thunderstorm, but chances increase toward the end of the week.

The week will be partly sunny to partly cloudy with scattered afternoon and evening showers or thunderstorms possible. It will be hot and humid with highs at least in the lower 90s each day, but beaches will be cooler. The best chance of storms is Thursday and Friday.

Forecast: 

Sunday: Partly to mostly sunny. Hot. Highs in the lower 90s but lower 80s lakefront

Sunday night: Mainly clear. Mild and muggy. Lows in the lower 70s

Monday: Partly to mostly sunny. Hot and humid. Highs in the lower to mid 90s but mid 80s lakefront