Average annual temperature is 11.9 °C
Absolute maximum temperature: 35.2 °C
Absolute minimum temperature: -20.6 °C
Number of sunny days: 202 days
Number of rainy days: 142 days
Number of snow days: 21 days
Look at detailed online map of Illinois City
* Weather data for Illinois City United States is based on climate observations for 2026 year
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Absolute maximum temperature (°C) | 13.7 | 11.4 | 21.9 | 25.3 | 32.0 | 33.8 | 34.3 | 35.2 | 32.6 | 30.0 | 18.3 | 14.1 |
| Average daytime temperature (°C) | 2.7 | 5.5 | 8.3 | 17.4 | 24.8 | 29.3 | 28.7 | 27.9 | 25.7 | 17.8 | 10.1 | 6.8 |
| Average temperature (°C) | -1.4 | -0.1 | 3.1 | 10.6 | 18.4 | 23.2 | 23.5 | 23.1 | 20.2 | 13.3 | 5.3 | 2.9 |
| Average night temperature (°C) | -4.3 | -4.7 | -0.8 | 5.2 | 12.4 | 17.3 | 18.7 | 18.8 | 15.7 | 9.5 | 1.3 | 0.4 |
| Absolute minimum temperature (°C) | -20.6 | -18.6 | -12.1 | -1.8 | 3.5 | 9.7 | 14.2 | 11.6 | 10.3 | -2.7 | -12.7 | -7.5 |
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight maximum duration (h) | 10.0 | 11.0 | 12.0 | 13.0 | 14.0 | 15.0 | 15.0 | 14.0 | 13.0 | 11.0 | 10.0 | 9.0 |
| Daylight mean duration (h) | 9.6 | 10.6 | 11.9 | 13.3 | 14.5 | 15.1 | 14.8 | 13.8 | 12.5 | 11.1 | 9.9 | 9.2 |
| Daylight minimum duration (h) | 9.0 | 10.0 | 11.0 | 12.0 | 13.0 | 14.0 | 14.0 | 13.0 | 11.0 | 10.0 | 9.0 | 9.0 |
| Sunshine mean duration (h) | 4.1 | 7.2 | 6.9 | 9.6 | 11.7 | 12.6 | 12.5 | 11.0 | 9.8 | 7.4 | 7.4 | 4.5 |
| Precipitation (mm) | 66 | 95 | 93 | 23 | 34 | 29 | 108 | 55 | 56 | 103 | 18 | 77 |
| Sunny days | 15 | 16 | 12 | 17 | 23 | 20 | 14 | 16 | 15 | 16 | 23 | 15 |
| Rainy days | 6 | 9 | 17 | 12 | 8 | 10 | 17 | 15 | 15 | 15 | 5 | 13 |
| Snow days | 10 | 3 | 2 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 2 | 3 |
The best time to visit Illinois City during the most sunny months:
The largest precipitation sum in Illinois City is at