Green Mountain, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 38 °F (low) to 58 °F (high). Annual precipitation averages 36.5 Inches. 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 | 10.4 °F | 27.3 °F | 1.03 in. |
| February | 14.2 °F | 32.1 °F | 1.16 in. |
| March | 25.5 °F | 45.1 °F | 2.05 in. |
| April | 36.8 °F | 59.3 °F | 3.75 in. |
| May | 49.5 °F | 70.6 °F | 5.02 in. |
| June | 60.1 °F | 80.2 °F | 5.44 in. |
| July | 63.3 °F | 83.4 °F | 4.25 in. |
| August | 60.6 °F | 81.3 °F | 4.19 in. |
| September | 51.7 °F | 75.5 °F | 3.47 in. |
| October | 39.5 °F | 62.0 °F | 2.64 in. |
| November | 27.3 °F | 46.2 °F | 1.97 in. |
| December | 16.6 °F | 33.1 °F | 1.48 in. |
| Annual | 38 °F | 58 °F | 36.45 in. |
| 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 : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |