Average annual temperature is 20.9 °C
Absolute maximum temperature: 35.8 °C
Absolute minimum temperature: -0.9 °C
Number of sunny days: 169 days
Number of rainy days: 196 days
Look at detailed online map of Alton
* Weather data for Alton 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) | 26.2 | 29.1 | 29.1 | 32.8 | 34.3 | 34.6 | 35.3 | 35.8 | 32.8 | 30.1 | 28.6 | 25.6 |
| Average daytime temperature (°C) | 20.5 | 23.6 | 24.6 | 28.0 | 29.3 | 31.0 | 32.7 | 33.3 | 30.5 | 26.4 | 21.7 | 18.5 |
| Average temperature (°C) | 14.1 | 17.2 | 18.4 | 21.4 | 23.1 | 25.5 | 27.6 | 27.9 | 24.9 | 20.8 | 16.3 | 13.4 |
| Average night temperature (°C) | 9.4 | 12.8 | 13.4 | 16.2 | 17.9 | 21.3 | 23.7 | 23.8 | 20.4 | 16.0 | 12.0 | 9.6 |
| Absolute minimum temperature (°C) | -0.9 | 2.9 | 2.6 | 10.4 | 12.5 | 18.4 | 22.0 | 21.7 | 16.5 | 7.9 | 2.1 | 1.4 |
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight maximum duration (h) | 10.0 | 11.0 | 12.0 | 13.0 | 13.0 | 14.0 | 14.0 | 13.0 | 12.0 | 11.0 | 10.0 | 10.0 |
| Daylight mean duration (h) | 10.5 | 11.1 | 12.0 | 12.9 | 13.7 | 14.0 | 13.9 | 13.2 | 12.3 | 11.4 | 10.7 | 10.2 |
| Daylight minimum duration (h) | 10.0 | 10.0 | 11.0 | 12.0 | 13.0 | 13.0 | 13.0 | 12.0 | 11.0 | 11.0 | 10.0 | 10.0 |
| Sunshine mean duration (h) | 8.0 | 8.5 | 9.4 | 10.0 | 11.3 | 10.6 | 11.0 | 11.3 | 10.1 | 9.7 | 7.0 | 6.6 |
| Precipitation (mm) | 54 | 96 | 97 | 57 | 73 | 262 | 105 | 179 | 78 | 41 | 54 | 126 |
| Sunny days | 18 | 21 | 14 | 12 | 11 | 5 | 5 | 8 | 13 | 24 | 18 | 20 |
| Rainy days | 13 | 7 | 17 | 18 | 20 | 25 | 26 | 23 | 17 | 7 | 12 | 11 |
| Snow days | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
The largest precipitation sum in Alton is at