| 2023 Hardiness Zone: | Zone 7a: 0°F to 5°F |
| 2012 Hardiness Zone: | 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. 21 - Apr. 30 |
| Koppen-Geiger Climate Zone: | Cfa - Humid Subtropical Climate |
| Ecoregion: | 72j - Southern Illinoian Till Plain |
| Heat Zone Days: | 91 - 120 days Over 86°F |
Annual Climate Data for ZIP Code 62946 - Harrisburg, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 22 | 26 | 35 | 45 | 54 | 63 | 67 | 65 | 57 | 45 | 36 | 26 | 45 |
| Avg Max Temp (°F) | 40 | 46 | 57 | 68 | 77 | 85 | 89 | 88 | 81 | 70 | 56 | 45 | 67 |
| Avg Precip (In.) | 3.18 | 3.1 | 4.45 | 4.57 | 4.95 | 4.36 | 3.91 | 3.23 | 3.04 | 3.03 | 4.24 | 3.89 | 45.96 |