Green Valley, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41.9 °F (low) to 62.8 °F (high). Annual precipitation averages 38.8 Inches. Green Valley is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 17.1 °F | 34.0 °F | 2.11 in. |
| February | 20.5 °F | 38.8 °F | 1.93 in. |
| March | 30.3 °F | 50.9 °F | 2.57 in. |
| April | 40.9 °F | 64.0 °F | 3.88 in. |
| May | 52.6 °F | 74.4 °F | 4.72 in. |
| June | 62.0 °F | 83.3 °F | 4.51 in. |
| July | 64.9 °F | 86.3 °F | 4.08 in. |
| August | 62.6 °F | 84.8 °F | 3.51 in. |
| September | 54.3 °F | 79.6 °F | 3.37 in. |
| October | 42.5 °F | 66.8 °F | 3.13 in. |
| November | 31.8 °F | 51.6 °F | 2.8 in. |
| December | 22.7 °F | 39.2 °F | 2.2 in. |
| Annual | 41.9 °F | 62.8 °F | 38.81 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |