Greenfield, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 43.5 °F (low) to 63.7 °F (high). Annual precipitation averages 40.2 Inches. Greenfield is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 19.6 °F | 36.1 °F | 2.2 in. |
| February | 23.1 °F | 41.3 °F | 2.04 in. |
| March | 32.0 °F | 52.5 °F | 3.11 in. |
| April | 42.4 °F | 64.8 °F | 4.34 in. |
| May | 53.9 °F | 74.6 °F | 4.88 in. |
| June | 62.9 °F | 83.1 °F | 4.55 in. |
| July | 66.3 °F | 86.2 °F | 3.69 in. |
| August | 63.9 °F | 85.2 °F | 3.24 in. |
| September | 55.5 °F | 79.5 °F | 3.22 in. |
| October | 44.1 °F | 67.3 °F | 3.26 in. |
| November | 33.5 °F | 53.0 °F | 3.37 in. |
| December | 24.5 °F | 41.0 °F | 2.28 in. |
| Annual | 43.5 °F | 63.7 °F | 40.18 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |