Roscoe, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 38.5 °F (low) to 57.8 °F (high). Annual precipitation averages 37.9 Inches. Roscoe 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 | 12.6 °F | 28.3 °F | 1.65 in. |
| February | 15.7 °F | 32.5 °F | 1.64 in. |
| March | 26.1 °F | 44.7 °F | 2.12 in. |
| April | 36.9 °F | 57.8 °F | 3.66 in. |
| May | 48.3 °F | 69.5 °F | 4.36 in. |
| June | 58.4 °F | 79.4 °F | 5.41 in. |
| July | 62.3 °F | 82.9 °F | 3.79 in. |
| August | 60.6 °F | 81.4 °F | 4.2 in. |
| September | 52.2 °F | 74.7 °F | 3.78 in. |
| October | 40.7 °F | 61.7 °F | 2.92 in. |
| November | 29.3 °F | 46.4 °F | 2.4 in. |
| December | 19.3 °F | 34.0 °F | 1.97 in. |
| Annual | 38.5 °F | 57.8 °F | 37.9 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 |