| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F | |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F 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 | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | 46 - 60 days Over 86°F |
Annual Climate Data for ZIP Code 62521 - Decatur, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 17 | 22 | 32 | 42 | 52 | 61 | 65 | 63 | 55 | 44 | 33 | 23 | 42 |
| Avg Max Temp (°F) | 34 | 40 | 52 | 65 | 76 | 84 | 88 | 86 | 80 | 68 | 52 | 39 | 64 |
| Avg Precip (In.) | 2 | 1.97 | 3.2 | 3.64 | 4.39 | 3.96 | 4.41 | 4.02 | 2.99 | 2.78 | 3.34 | 2.81 | 39.51 |