New Vienna, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2.4 °C (low) to 13.6 °C (high). Annual precipitation averages 984 Millimeters. New Vienna 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 | -12.8 °C | -3.3 °C | 31.5 mm |
| February | -10.8 °C | -0.8 °C | 34.54 mm |
| March | -4.3 °C | 6.4 °C | 53.59 mm |
| April | 1.9 °C | 14.2 °C | 98.81 mm |
| May | 8.4 °C | 20.5 °C | 118.11 mm |
| June | 14.2 °C | 25.8 °C | 148.34 mm |
| July | 16.2 °C | 27.6 °C | 122.17 mm |
| August | 14.8 °C | 26.6 °C | 105.41 mm |
| September | 10 °C | 22.9 °C | 96.77 mm |
| October | 3.4 °C | 15.8 °C | 75.69 mm |
| November | -3.1 °C | 7.1 °C | 56.64 mm |
| December | -9 °C | -0.1 °C | 42.42 mm |
| Annual | 2.4 °C | 13.6 °C | 983.99 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 | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |