Clarksville, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3 °C (low) to 14.1 °C (high). Annual precipitation averages 925.8 Millimeters. Clarksville is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -12.9 °C | -3.3 °C | 24.64 mm |
| February | -10.5 °C | -0.9 °C | 27.94 mm |
| March | -4.1 °C | 6.4 °C | 47.24 mm |
| April | 2.4 °C | 14.9 °C | 97.54 mm |
| May | 9.4 °C | 21.6 °C | 126.24 mm |
| June | 15.5 °C | 26.9 °C | 147.83 mm |
| July | 17.2 °C | 28.5 °C | 113.28 mm |
| August | 15.7 °C | 27.3 °C | 104.9 mm |
| September | 10.9 °C | 24.1 °C | 88.65 mm |
| October | 4.1 °C | 16.6 °C | 66.8 mm |
| November | -3 °C | 7.3 °C | 45.21 mm |
| December | -9.1 °C | -0.2 °C | 35.56 mm |
| Annual | 3 °C | 14.1 °C | 925.83 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |