Twin Grove, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41.2 °F (low) to 61.5 °F (high). Annual precipitation averages 38.8 Inches. Twin Grove is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 16.0 °F | 32.4 °F | 2.33 in. |
| February | 19.5 °F | 37.3 °F | 1.92 in. |
| March | 28.8 °F | 49.4 °F | 2.71 in. |
| April | 39.8 °F | 62.7 °F | 3.81 in. |
| May | 51.4 °F | 73.4 °F | 4.61 in. |
| June | 61.1 °F | 82.3 °F | 4.17 in. |
| July | 64.2 °F | 85.5 °F | 3.83 in. |
| August | 62.3 °F | 83.5 °F | 3.66 in. |
| September | 54.5 °F | 78.4 °F | 3.3 in. |
| October | 43.0 °F | 65.3 °F | 3.31 in. |
| November | 31.6 °F | 50.3 °F | 2.82 in. |
| December | 21.9 °F | 37.6 °F | 2.36 in. |
| Annual | 41.2 °F | 61.5 °F | 38.83 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 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 |