Illinois in september: average Weather, Temperature and Climate
Weather in Illinois in september 2025
The weather in Illinois in september comes from statistical datas on the past years. You can view the weather statistics for all the month, but also by clicking on the tabs for the beginning, the middle and the end of the month.
Average weather throughout september
good weather UV index: 6
Weather at 6am
59°F
Clear/Sunny
36% of time
28%
16%
9%
Weather at 12pm
76°F
Clear/Sunny
54% of time
23%
10%
9%
Weather at 6pm
70°F
Clear/Sunny
58% of time
24%
9%
5%
Weather at 3am
61°F
41%
21%
16%
13%
Evolution of daily average temperature and precipitation in Illinois in september
These charts show the evolution of average minimum/maximum temperatures as well as average daily precipitation volume in Illinois in september.
The climate of Illinois in september is good
The weather in september in Illinois is quite dry (with 2.9in of rainfall over 5 days). This is better than the previous month since in august it receives an average of 3.5in of precipitation over 6 days.
The climate enjoyable in this location september. The high seasonal norm is 77°F. On average, the recorded minimum temperature is 59°F. Thus, the mean temperature average on this month of september in Illinois is 68°F. Note that seasonal normals in contrast with those observed in Illinois in the month of september with a maximum record of 95°F in 2013 and a minimum record of 38°F in 2012. You can expect to have about 4 days with temperatures up to 86°F, or 13 of time.
On average, in Illinois, the days of september last 12:27. The sun rises at 05:39 and sunset is at 18:06.
With a good weather, this month is recommended to go in Illinois in United States.
Seasonal average climate and temperature of Illinois in september
Check below seasonal norms These datas are compiled from the weather statements earlier years of the month of september.
| September | |||||
| Outside temperature | |||||
| Average temperature | 68°F | ||||
| Highest temperature | 77°F | ||||
| Lowest temperature | 59°F | ||||
| Highest record temperature | 95°F (2013) | ||||
| Lowest record temperature | 38°F (2012) | ||||
| Number of days at +86°F | 4 day(s) (13%) | ||||
| Number of days at +65°F | 28 day(s) (93%) | ||||
| Number of days at -32°F | 0 day(s) (0%) | ||||
| Wind | |||||
| Wind speed | 17km/h | ||||
| Wind temperature | 59°F | ||||
| Precipitation (rainfall) | |||||
| Rainfall | 2.9in | ||||
| Number of days with rainfall | 5 day(s) (16%) | ||||
| Record daily rainfall | 2.8in (2012) | ||||
| Snowfall | 0cm | ||||
| Other climate data | |||||
| Humidity | 90% | ||||
| Visibility | 8.96km | ||||
| Cloud cover | 28% | ||||
| UV index | 6 | ||||
| Daily sunshine hours | 12 | ||||
| Sunrise and sunset | |||||
| Time of sunrise | 05:39 | ||||
| Time of sunset | 18:06 | ||||
| Length of day | 12:27 | ||||
| Our opinion about the weather in september | |||||
| Our opinion at whereandwhen.net | good | ||||
How was the weather last september?
Here is the day by day recorded weather in Illinois in september 2024:
61°F to 79°F
54°F to 76°F
54°F to 79°F
54°F to 86°F
65°F to 88°F
63°F to 74°F
43°F to 70°F
43°F to 76°F
52°F to 85°F
58°F to 86°F
61°F to 92°F
63°F to 94°F
65°F to 77°F
63°F to 88°F
67°F to 92°F
67°F to 94°F
59°F to 85°F
58°F to 86°F
61°F to 86°F
67°F to 86°F
65°F to 86°F
65°F to 70°F
54°F to 76°F
59°F to 68°F
49°F to 74°F
54°F to 77°F
58°F to 74°F
65°F to 70°F
63°F to 77°F
65°F to 77°F
Map: other cities in the United States (USA) in september
Cities near Illinois:
| Chicago in september | good weather |
| St. Louis (Missouri) in september | good weather |
| Indianapolis in september | good weather |
| Wisconsin in september | good weather |
| Missouri in september | good weather |
| Des Moines in september | good weather |
| Louisville (Kentucky) in september | good weather |
| Cincinnati in september | good weather |
| Kansas City in september | good weather |
| Nashville in september | good weather |
| Detroit in september | good weather |
| Minneapolis (Minnesota) in september | perfect weather |
Click over cities on the map for information about the weather in september.
Illinois
perfect weather
good
tolerable
bad
very bad
Weather data for Illinois in september:
Weather data for Illinois for september 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.