It's said that when you first move, life is full of surprises in Chicago. The summer is short - probably only two months, but boy, it can get hot. You'll have plenty of winter weather later.
The Polish element is strong there, meaning interesting food as well as company. Be prepared for wind and wet and more wind. Best buy an umbrella with wind vents. Your bike may well get vandalised and parking is a pain, so it's a case of be prepared.