Montpelier, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.2 °C (low) to 15.9 °C (high). Annual precipitation averages 961.1 Millimeters. Montpelier is located in USDA Plant Hardiness Zone 5b. 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 | -9.6 °C | -0.7 °C | 36.58 mm |
| February | -7.6 °C | 1.8 °C | 43.43 mm |
| March | -1.6 °C | 9 °C | 61.98 mm |
| April | 4.6 °C | 16.5 °C | 93.73 mm |
| May | 11.2 °C | 22.6 °C | 123.7 mm |
| June | 16.7 °C | 27.8 °C | 125.98 mm |
| July | 18.7 °C | 29.6 °C | 105.41 mm |
| August | 17.4 °C | 28.5 °C | 101.6 mm |
| September | 12.9 °C | 25.2 °C | 90.68 mm |
| October | 6.3 °C | 18.1 °C | 72.64 mm |
| November | -0.3 °C | 9.6 °C | 56.9 mm |
| December | -6.2 °C | 2.3 °C | 48.51 mm |
| Annual | 5.2 °C | 15.9 °C | 961.14 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 5b : -26.1°C to -23.3°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 |