Bonaparte, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 42.5 °F (low) to 62.6 °F (high). Annual precipitation averages 38.1 Inches. Bonaparte is located in USDA Plant Hardiness Zone 6a. 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 | 16.7 °F | 33.5 °F | 1.47 in. |
| February | 20.1 °F | 38.1 °F | 1.78 in. |
| March | 30.7 °F | 50.7 °F | 2.32 in. |
| April | 41.5 °F | 64.2 °F | 3.74 in. |
| May | 52.9 °F | 74.4 °F | 5.33 in. |
| June | 62.5 °F | 83.6 °F | 4.86 in. |
| July | 66.4 °F | 87.4 °F | 4.13 in. |
| August | 64.3 °F | 85.9 °F | 3.75 in. |
| September | 55.8 °F | 78.7 °F | 3.71 in. |
| October | 44.2 °F | 65.4 °F | 3.0 in. |
| November | 32.6 °F | 50.7 °F | 2.29 in. |
| December | 22.5 °F | 38.4 °F | 1.76 in. |
| Annual | 42.5 °F | 62.6 °F | 38.14 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 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |