Chicago Weather In December 2025. United states | chicago, illinois. Here's what noaa says about this year, and la niña.

A shift in chicago’s weather is observed as november turns into december, with the average high temperature reducing from a frosty 46°f (7.8°c) to a cold 35.8°f (2.1°c). April and may will be warmer than normal, with rainfall above normal in the east and below normal in the west.