Farnhamville, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3 °C (low) to 14.4 °C (high). Annual precipitation averages 878.6 Millimeters. Farnhamville 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -12.6 °C | -2.8 °C | 21.34 mm |
| February | -10.3 °C | -0.2 °C | 27.69 mm |
| March | -3.8 °C | 7.2 °C | 50.55 mm |
| April | 2.3 °C | 15.3 °C | 93.47 mm |
| May | 9.3 °C | 21.4 °C | 127.76 mm |
| June | 15.3 °C | 26.8 °C | 129.03 mm |
| July | 17.3 °C | 28.6 °C | 101.85 mm |
| August | 15.8 °C | 27.3 °C | 107.44 mm |
| September | 10.7 °C | 24.1 °C | 79.76 mm |
| October | 3.8 °C | 16.9 °C | 65.53 mm |
| November | -3.2 °C | 7.7 °C | 40.89 mm |
| December | -9.1 °C | 0.2 °C | 33.27 mm |
| Annual | 3 °C | 14.4 °C | 878.58 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 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |