| 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. 11 - Apr. 20 |
| Koppen-Geiger Climate Zone: | Cfa - Humid Subtropical Climate |
| Ecoregion: | 72j - Southern Illinoian Till Plain |
| Heat Zone Days: | 46 - 60 days Over 86°F |
Annual Climate Data for ZIP Code 62948 - Herrin, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 20 | 24 | 34 | 43 | 53 | 62 | 66 | 63 | 56 | 44 | 35 | 25 | 44 |
| Avg Max Temp (°F) | 39 | 45 | 56 | 66 | 76 | 84 | 88 | 87 | 80 | 69 | 56 | 44 | 66 |
| Avg Precip (In.) | 3.03 | 3.03 | 4.35 | 4.44 | 4.76 | 4.38 | 3.65 | 3.64 | 3.11 | 3.04 | 4.55 | 3.71 | 45.7 |