Average annual temperature is 11.2 °C
Absolute maximum temperature: 36.2 °C
Absolute minimum temperature: -21.1 °C
Number of sunny days: 185 days
Number of rainy days: 163 days
Number of snow days: 17 days
Look at detailed online map of Romeoville
* Weather data for Romeoville 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) | 12.4 | 14.1 | 20.6 | 25.3 | 31.3 | 32.1 | 33.4 | 36.2 | 33.3 | 27.5 | 19.4 | 14.6 |
| Average daytime temperature (°C) | 3.3 | 5.9 | 8.1 | 16.5 | 22.7 | 27.7 | 28.4 | 27.4 | 24.3 | 16.7 | 9.6 | 6.6 |
| Average temperature (°C) | -0.6 | 0.4 | 2.8 | 9.8 | 16.0 | 20.9 | 22.7 | 22.0 | 19.2 | 12.4 | 4.8 | 3.1 |
| Average night temperature (°C) | -3.5 | -3.7 | -0.9 | 4.0 | 10.3 | 15.1 | 17.9 | 17.7 | 15.3 | 9.0 | 0.9 | 0.6 |
| Absolute minimum temperature (°C) | -21.1 | -19.9 | -11.5 | -3.2 | 1.4 | 7.7 | 14.3 | 12.3 | 9.7 | -2.9 | -10.5 | -7.9 |
| 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 | 14.9 | 13.8 | 12.5 | 11.1 | 9.9 | 9.2 |
| Daylight minimum duration (h) | 9.0 | 10.0 | 11.0 | 12.0 | 14.0 | 14.0 | 14.0 | 13.0 | 11.0 | 10.0 | 9.0 | 9.0 |
| Sunshine mean duration (h) | 3.1 | 7.7 | 6.2 | 9.1 | 10.6 | 12.0 | 11.5 | 10.7 | 8.1 | 6.5 | 7.3 | 4.2 |
| Precipitation (mm) | 59 | 83 | 114 | 112 | 47 | 32 | 186 | 135 | 147 | 110 | 38 | 70 |
| Sunny days | 11 | 17 | 12 | 14 | 20 | 19 | 14 | 16 | 13 | 10 | 23 | 16 |
| Rainy days | 11 | 9 | 16 | 16 | 11 | 11 | 17 | 15 | 17 | 20 | 6 | 14 |
| Snow days | 9 | 2 | 3 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 |
The best time to visit Romeoville during the most sunny months:
The largest precipitation sum in Romeoville is at