| 2023 Hardiness Zone: | Zone 6b: -5°F to 0°F |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F |
| 1990 Hardiness Zone: | Zone 1b: -15F to -10F |
| Average First Frost Date: | Oct. 11 - Oct. 20 |
| Average Last Frost Date: | Apr. 11 - Apr. 20 |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers |
| Ecoregion: | 72j - Southern Illinoian Till Plain |
| Heat Zone Days: | 61 - 90 days Over 86°F |
Annual Climate Data for ZIP Code 62049 - Hillsboro, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 18 | 23 | 33 | 43 | 53 | 62 | 66 | 63 | 55 | 45 | 34 | 24 | 43 |
| Avg Max Temp (°F) | 36 | 42 | 54 | 66 | 76 | 84 | 88 | 86 | 80 | 69 | 53 | 41 | 65 |
| Avg Precip (In.) | 2.18 | 2.04 | 3.53 | 4.12 | 4.29 | 4.04 | 3.59 | 3.49 | 3.14 | 2.89 | 3.8 | 3 | 40.12 |