The weather in Illinois in December is very cold with temperatures between 28°F and 37°F, warm clothes are a must.
You can expect about 3 to 8 days of rain in Illinois during the month of December. It’s a good idea to bring along your umbrella so that you don’t get caught in poor weather.
Illinois is going to experience quite a number of days of snow during December. It’s the perfect time to build snowmen, drink hot cocoa, and have a snowball fight. Just remember to wear a warm scarf and a pair of mittens!
Our weather forecast can give you a great sense of what weather to expect in Illinois in December 2025.
If you’re planning to visit Illinois in the near future, we highly recommend that you review the 14 day weather forecast for Illinois before you arrive.
