illinois average summer temperature
Illinois has a temperate climate, with cold, snowy winters and hot, wet summersâideal weather for corn and hogs. The seasons are sharply differentiated: mean winter temperatures are 22Â°F (â6Â°C) in the north and 37Â°F (3Â°C) in the south; mean summer temperatures are 70Â°F (21Â°C) in the north and 77Â°F (25Â°C) in the south.