Farmington, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6 °C (low) to 17 °C (high). Annual precipitation averages 981.5 Millimeters. Farmington is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.4 °C | 0.8 °C | 38.1 mm |
| February | -6.4 °C | 3.4 °C | 45.72 mm |
| March | -0.7 °C | 10.4 °C | 60.96 mm |
| April | 5.4 °C | 17.9 °C | 95.25 mm |
| May | 11.8 °C | 23.6 °C | 134.37 mm |
| June | 17.2 °C | 28.7 °C | 125.48 mm |
| July | 19.3 °C | 30.8 °C | 106.93 mm |
| August | 18.1 °C | 29.9 °C | 96.52 mm |
| September | 13.4 °C | 25.9 °C | 94.74 mm |
| October | 6.9 °C | 18.6 °C | 77.72 mm |
| November | 0.4 °C | 10.5 °C | 59.69 mm |
| December | -5.2 °C | 3.6 °C | 45.97 mm |
| Annual | 6 °C | 17 °C | 981.45 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 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 |