| 2023 Hardiness Zone: | Zone 6b: -5°F to 0°F Zone 7a: 0°F to 5°F |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 6b: -5°F to 0°F |
| 1990 Hardiness Zone: | Zone 6a: -10F to -5F |
| Average First Frost Date: | Oct. 11 - Oct. 20 |
| Average Last Frost Date: | Apr. 11 - Apr. 20 |
| Koppen-Geiger Climate Zone: | Cfa - Humid Subtropical Climate |
| Ecoregion: | 72j - Southern Illinoian Till Plain |
| Heat Zone Days: | 61 - 90 days Over 86°F |
Annual Climate Data for ZIP Code 62221 - Belleville, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 21 | 26 | 35 | 44 | 54 | 63 | 67 | 65 | 57 | 46 | 36 | 26 | 45 |
| Avg Max Temp (°F) | 39 | 45 | 56 | 67 | 77 | 85 | 89 | 87 | 81 | 70 | 55 | 43 | 66 |
| Avg Precip (In.) | 2.11 | 2.26 | 3.58 | 3.91 | 4.2 | 3.91 | 3.61 | 3.32 | 3.09 | 2.9 | 3.93 | 3.03 | 39.87 |