Roanoke, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41 °F (low) to 61.6 °F (high). Annual precipitation averages 37.9 Inches. Roanoke 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 | 15.9 °F | 32.4 °F | 2.24 in. |
| February | 19.3 °F | 37.3 °F | 1.97 in. |
| March | 28.9 °F | 49.5 °F | 2.66 in. |
| April | 39.6 °F | 62.7 °F | 3.69 in. |
| May | 51.3 °F | 73.6 °F | 4.51 in. |
| June | 61.0 °F | 82.4 °F | 4.18 in. |
| July | 64.2 °F | 85.5 °F | 3.79 in. |
| August | 62.1 °F | 83.7 °F | 3.49 in. |
| September | 54.1 °F | 78.6 °F | 3.63 in. |
| October | 42.5 °F | 65.6 °F | 3.05 in. |
| November | 31.4 °F | 50.4 °F | 2.62 in. |
| December | 21.7 °F | 37.7 °F | 2.11 in. |
| Annual | 41 °F | 61.6 °F | 37.94 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 | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |