Otterville, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7.3 °C (low) to 18.2 °C (high). Annual precipitation averages 1057.4 Millimeters. Otterville is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.9 °C | 3.3 °C | 62.23 mm |
| February | -4.1 °C | 6.3 °C | 57.4 mm |
| March | 0.9 °C | 12.2 °C | 81.53 mm |
| April | 6.8 °C | 18.6 °C | 117.35 mm |
| May | 12.9 °C | 23.9 °C | 126.75 mm |
| June | 18.1 °C | 28.7 °C | 107.7 mm |
| July | 19.9 °C | 30.6 °C | 94.23 mm |
| August | 18.8 °C | 30 °C | 92.96 mm |
| September | 14 °C | 26.4 °C | 85.09 mm |
| October | 7.7 °C | 20 °C | 80.01 mm |
| November | 1.6 °C | 12.2 °C | 86.61 mm |
| December | -3.3 °C | 5.9 °C | 65.53 mm |
| Annual | 7.3 °C | 18.2 °C | 1057.39 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |