Long Grove, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40.3 °F (low) to 58.5 °F (high). Annual precipitation averages 37.7 Inches. Long 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 | 15.5 °F | 30.7 °F | 1.97 in. |
| February | 18.2 °F | 34.3 °F | 1.98 in. |
| March | 27.5 °F | 45.3 °F | 2.28 in. |
| April | 37.8 °F | 57.7 °F | 3.79 in. |
| May | 48.6 °F | 68.9 °F | 4.46 in. |
| June | 58.6 °F | 79.1 °F | 4.46 in. |
| July | 64.0 °F | 83.5 °F | 3.78 in. |
| August | 62.7 °F | 81.5 °F | 3.95 in. |
| September | 54.6 °F | 74.9 °F | 3.32 in. |
| October | 42.7 °F | 62.0 °F | 3.26 in. |
| November | 31.4 °F | 47.8 °F | 2.37 in. |
| December | 21.5 °F | 36.0 °F | 2.1 in. |
| Annual | 40.3 °F | 58.5 °F | 37.72 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 | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |