The Chicago area lies at the northern limit of a snow area that is occurring today across Illinois (and areas to the west and east of the state). Very heavy snow is occurring across central and south Illinois, with lighter snow amounts north of there and rain to the south. Snow totals across metropolitan Chicago will range from an inch or less at the Wisconsin border to a couple inches in the city and three or four inches at Interstate 80. Southward from there, snows increase significantly to totals of 12 inches or perhaps more. Snow diminishes and ends by Sunday.
Chilly but not genuinely cold air follows in behind the storm system, with highs in the middle 30s on Sunday. Then moderately warmer air of Pacific origin arrives Monday and Tuesday, with afternoon temperatures on Tuesday reaching the lower 40s.