Montpelier, Idaho has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 26.5 °F (low) to 54.9 °F (high). Annual precipitation averages 15.3 Inches. Montpelier is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around Jun. 1 - Jun. 10 through the first frost around Sep.1 - Sep. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 6.8 °F | 29.2 °F | 1.61 in. |
| February | 8.3 °F | 32.3 °F | 1.36 in. |
| March | 17.9 °F | 41.9 °F | 1.35 in. |
| April | 26.5 °F | 52.2 °F | 1.41 in. |
| May | 34.4 °F | 62.4 °F | 2.09 in. |
| June | 41.0 °F | 72.7 °F | 1.23 in. |
| July | 46.6 °F | 82.8 °F | 0.65 in. |
| August | 45.9 °F | 82.2 °F | 0.82 in. |
| September | 36.1 °F | 72.5 °F | 1.24 in. |
| October | 27.1 °F | 58.1 °F | 1.25 in. |
| November | 18.2 °F | 42.3 °F | 1.19 in. |
| December | 9.1 °F | 30.6 °F | 1.1 in. |
| Annual | 26.5 °F | 54.9 °F | 15.3 in. |
| Average First Frost Date | Sep.1 - Sep. 10 |
| Average Last Frost Date | Jun. 1 - Jun. 10 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |