Clarksville, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37.4 °F (low) to 57.4 °F (high). Annual precipitation averages 36.5 Inches. 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 | 8.8 °F | 26.0 °F | 0.97 in. |
| February | 13.1 °F | 30.3 °F | 1.1 in. |
| March | 24.6 °F | 43.6 °F | 1.86 in. |
| April | 36.4 °F | 58.9 °F | 3.84 in. |
| May | 49.0 °F | 70.9 °F | 4.97 in. |
| June | 59.9 °F | 80.5 °F | 5.82 in. |
| July | 63.0 °F | 83.3 °F | 4.46 in. |
| August | 60.3 °F | 81.2 °F | 4.13 in. |
| September | 51.7 °F | 75.3 °F | 3.49 in. |
| October | 39.3 °F | 61.8 °F | 2.63 in. |
| November | 26.6 °F | 45.1 °F | 1.78 in. |
| December | 15.7 °F | 31.6 °F | 1.4 in. |
| Annual | 37.4 °F | 57.4 °F | 36.45 in. |
| 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 : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |