Sidney, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 42.2 °F (low) to 62.1 °F (high). Annual precipitation averages 39.9 Inches. Sidney is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 18.1 °F | 33.9 °F | 2.3 in. |
| February | 21.2 °F | 38.4 °F | 2.06 in. |
| March | 30.4 °F | 50.2 °F | 2.78 in. |
| April | 41.0 °F | 63.6 °F | 4.1 in. |
| May | 52.6 °F | 74.0 °F | 4.45 in. |
| June | 61.8 °F | 82.3 °F | 4.8 in. |
| July | 64.4 °F | 84.5 °F | 4.17 in. |
| August | 62.0 °F | 83.1 °F | 3.03 in. |
| September | 54.8 °F | 78.6 °F | 3.21 in. |
| October | 43.1 °F | 66.0 °F | 3.35 in. |
| November | 32.5 °F | 51.3 °F | 3.24 in. |
| December | 23.9 °F | 38.8 °F | 2.43 in. |
| Annual | 42.2 °F | 62.1 °F | 39.92 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 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 |