Bonaparte, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.8 °C (low) to 17 °C (high). Annual precipitation averages 968.8 Millimeters. 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 | -8.5 °C | 0.8 °C | 37.34 mm |
| February | -6.6 °C | 3.4 °C | 45.21 mm |
| March | -0.7 °C | 10.4 °C | 58.93 mm |
| April | 5.3 °C | 17.9 °C | 95 mm |
| May | 11.6 °C | 23.6 °C | 135.38 mm |
| June | 16.9 °C | 28.7 °C | 123.44 mm |
| July | 19.1 °C | 30.8 °C | 104.9 mm |
| August | 17.9 °C | 29.9 °C | 95.25 mm |
| September | 13.2 °C | 25.9 °C | 94.23 mm |
| October | 6.8 °C | 18.6 °C | 76.2 mm |
| November | 0.3 °C | 10.4 °C | 58.17 mm |
| December | -5.3 °C | 3.6 °C | 44.7 mm |
| Annual | 5.8 °C | 17 °C | 968.75 mm |
| 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 : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |