Green Mountain, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.3 °C (low) to 14.5 °C (high). Annual precipitation averages 925.8 Millimeters. Green Mountain 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 °C | -2.6 °C | 26.16 mm |
| February | -9.9 °C | 0.1 °C | 29.46 mm |
| March | -3.6 °C | 7.3 °C | 52.07 mm |
| April | 2.7 °C | 15.2 °C | 95.25 mm |
| May | 9.7 °C | 21.4 °C | 127.51 mm |
| June | 15.6 °C | 26.8 °C | 138.18 mm |
| July | 17.4 °C | 28.6 °C | 107.95 mm |
| August | 15.9 °C | 27.4 °C | 106.43 mm |
| September | 10.9 °C | 24.2 °C | 88.14 mm |
| October | 4.2 °C | 16.7 °C | 67.06 mm |
| November | -2.6 °C | 7.9 °C | 50.04 mm |
| December | -8.6 °C | 0.6 °C | 37.59 mm |
| Annual | 3.3 °C | 14.5 °C | 925.84 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 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 |