Illinois in december: average Weather, Temperature and Climate
Weather in Illinois in december 2026
The weather in Illinois in the month of december comes from statistical datas on the past years. You can view the weather statistics for the whole month, but also by using the tabs for the beginning, the middle and the end of the month.
Average weather throughout december
very bad weather 105.4cm
Weather at 6am
31°F
Clear/Sunny
31% of time
30%
21%
8%
Weather at 12pm
38°F
Clear/Sunny
34% of time
33%
20%
7%
Weather at 6pm
34°F
Clear/Sunny
37% of time
28%
18%
7%
Weather at 3am
32°F
34%
21%
17%
13%
Evolution of daily average temperature and precipitation in Illinois in december
These charts show the evolution of average minimum/maximum temperatures as well as average daily precipitation volume in Illinois in december.
The climate of Illinois in december is very bad
the weather in Illinois in december is rather dry (with 1.9in of rainfall over 3 days). It should be noted an improvement from the previous month since in november it receives an average of 2.4in of rainfall over 3 days.
The climate is quite more than very fresh in this location december. Plan a sweater! The high seasonal norm is 40°F. The minimum is 31°F. Thus, the mean temperature average on this month of december in Illinois is 34°F. Note that seasonal normals in contrast with those observed in Illinois in december with a maximum record of 67°F in 2012 and a minimum record of -4°F in 2017. You need to prepare to have about 20 days with temperatures down below 32°F, or 65% of time.
Day length in Illinois in december is 09:16. Sunrise is at 07:15 and sets at 16:31.
December: another location in the United States (USA)?
If you want to go to the United States (USA) in december, there are destinations with better weather than Illinois:
In december, Miami (Florida) has perfect weather.
Furthermore, Hawaii (Honolulu), Houston, Myrtle Beach, Phoenix (Arizona), Carolina Beach and Dauphin Island (Alabama) have good weather.
Finally, California, Louisiana, Atlanta, Dallas, Austin and Big Bend National Park (Texas) have a tolerable climate, but better than Illinois.
Seasonal average climate and temperature of Illinois in december
Check below seasonal norms These datas are compiled from the weather statements of the last years of december.
| December | |||||
| Outside temperature | |||||
| Average temperature | 34°F | ||||
| Highest temperature | 40°F | ||||
| Lowest temperature | 31°F | ||||
| Highest record temperature | 67°F (2012) | ||||
| Lowest record temperature | -4°F (2017) | ||||
| Number of days at +65°F | 0 day(s) (0%) | ||||
| Number of days at -32°F | 20 day(s) (65%) | ||||
| Wind | |||||
| Wind speed | 21km/h | ||||
| Wind temperature | 22°F | ||||
| Precipitation (rainfall) | |||||
| Rainfall | 1.9in | ||||
| Number of days with rainfall | 3 day(s) (9%) | ||||
| Record daily rainfall | 1in (2009) | ||||
| Snowfall | 105.4cm | ||||
| Other climate data | |||||
| Humidity | 84% | ||||
| Visibility | 8.81km | ||||
| Cloud cover | 51% | ||||
| UV index | 2 | ||||
| Daily sunshine hours | 7 | ||||
| Sunrise and sunset | |||||
| Time of sunrise | 07:15 | ||||
| Time of sunset | 16:31 | ||||
| Length of day | 09:16 | ||||
| Our opinion about the weather in december | |||||
| Our opinion at whereandwhen.net | very bad | ||||
How was the weather last december?
Here is the day by day recorded weather in Illinois in december 2025:
22°F to 27°F
20°F to 29°F
23°F to 32°F
9°F to 20°F
13°F to 32°F
31°F to 32°F
32°F to 34°F
22°F to 29°F
25°F to 38°F
27°F to 40°F
25°F to 29°F
31°F to 32°F
14°F to 25°F
4°F to 11°F
7°F to 31°F
18°F to 34°F
31°F to 34°F
38°F to 41°F
18°F to 27°F
27°F to 38°F
25°F to 34°F
29°F to 38°F
34°F to 36°F
31°F to 36°F
34°F to 38°F
41°F to 43°F
40°F to 47°F
54°F to 63°F
16°F to 23°F
14°F to 29°F
29°F to 32°F
Map: other cities in the United States (USA) in december
Cities near Illinois:
| Chicago in december | very bad weather |
| St. Louis (Missouri) in december | very bad weather |
| Indianapolis in december | very bad weather |
| Wisconsin in december | very bad weather |
| Missouri in december | very bad weather |
| Des Moines in december | very bad weather |
| Louisville (Kentucky) in december | very bad weather |
| Cincinnati in december | very bad weather |
| Kansas City in december | very bad weather |
| Nashville in december | very bad weather |
| Detroit in december | very bad weather |
| Minneapolis (Minnesota) in december | very bad weather |
Click over cities on the map for information about the weather in december.
Illinois
perfect weather
good
tolerable
bad
very bad
Weather data for Illinois in december:
Weather data for Illinois for december are derived from an average of the weather forecast since 2009 in Illinois. There is a margin of error and these forecasts are to be considered as general information only. The weather in Illinois can vary slightly from year to year, but this data should limit surprises. So you can pack your bags or check for the best time in year to go to Illinois.