| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F |
| 2012 Hardiness Zone: | Zone 5b: -15°F to -10°F |
| 1990 Hardiness Zone: | Zone 1b: -15F to -10F |
| Average First Frost Date: | Oct. 11 - Oct. 20 |
| Average Last Frost Date: | Apr. 21 - Apr. 30 |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers |
| Ecoregion: | 54a - Illinois/Indiana Prairies |
| Heat Zone Days: | 15 - 30 days Over 86°F |
Annual Climate Data for ZIP Code 62675 - Petersburg, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 16 | 21 | 31 | 41 | 52 | 61 | 65 | 63 | 55 | 43 | 33 | 22 | 42 |
| Avg Max Temp (°F) | 33 | 39 | 51 | 64 | 75 | 84 | 87 | 85 | 79 | 67 | 51 | 38 | 63 |
| Avg Precip (In.) | 1.62 | 1.77 | 3.05 | 3.53 | 4.29 | 3.81 | 3.85 | 3.46 | 3.09 | 2.77 | 3.04 | 2.54 | 36.83 |