| 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. 21 - Oct. 31 |
| 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 62298 - Waterloo, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 20 | 25 | 35 | 44 | 54 | 64 | 68 | 66 | 58 | 46 | 36 | 25 | 45 |
| Avg Max Temp (°F) | 38 | 44 | 55 | 66 | 76 | 84 | 89 | 87 | 80 | 69 | 55 | 42 | 65 |
| Avg Precip (In.) | 2.31 | 2.39 | 3.73 | 4.1 | 4.09 | 3.97 | 4.1 | 3.17 | 3.36 | 3.04 | 4.21 | 3.32 | 41.78 |