New Hartford, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3 °C (low) to 14.1 °C (high). Annual precipitation averages 940.8 Millimeters. New Hartford 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 | -12.7 °C | -3.2 °C | 24.64 mm |
| February | -10.4 °C | -0.7 °C | 28.45 mm |
| March | -4.1 °C | 6.7 °C | 51.31 mm |
| April | 2.5 °C | 14.8 °C | 100.58 mm |
| May | 9.6 °C | 21.3 °C | 124.46 mm |
| June | 15.6 °C | 26.7 °C | 147.07 mm |
| July | 17.3 °C | 28.3 °C | 115.57 mm |
| August | 15.7 °C | 27.2 °C | 105.66 mm |
| September | 10.8 °C | 23.9 °C | 86.87 mm |
| October | 3.8 °C | 16.5 °C | 70.36 mm |
| November | -3.1 °C | 7.5 °C | 47.5 mm |
| December | -9 °C | 0.2 °C | 38.35 mm |
| Annual | 3 °C | 14.1 °C | 940.82 mm |
| 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 : -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 |