Poplar Grove, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 38.1 °F (low) to 57.7 °F (high). Annual precipitation averages 37.9 Inches. Poplar Grove is located in USDA Plant Hardiness Zone 5b. 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 | 12.9 °F | 28.7 °F | 1.65 in. |
| February | 15.9 °F | 32.8 °F | 1.64 in. |
| March | 25.6 °F | 44.7 °F | 2.15 in. |
| April | 36.1 °F | 57.7 °F | 3.7 in. |
| May | 47.7 °F | 69.3 °F | 4.43 in. |
| June | 57.5 °F | 79.0 °F | 5.41 in. |
| July | 61.5 °F | 82.6 °F | 3.89 in. |
| August | 59.7 °F | 81.0 °F | 4.13 in. |
| September | 51.8 °F | 74.5 °F | 3.63 in. |
| October | 40.3 °F | 61.4 °F | 2.89 in. |
| November | 29.4 °F | 46.5 °F | 2.36 in. |
| December | 18.9 °F | 33.9 °F | 1.99 in. |
| Annual | 38.1 °F | 57.7 °F | 37.87 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 5b : -15°F to -10°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 |