Grangeville, Idaho has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 35.2 °F (low) to 57.5 °F (high). Annual precipitation averages 23.6 Inches. Grangeville is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Jun. 1 - Jun. 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 23.4 °F | 37.2 °F | 1.2 in. |
| February | 24.7 °F | 40.9 °F | 1.45 in. |
| March | 28.5 °F | 48.0 °F | 2.51 in. |
| April | 33.0 °F | 55.1 °F | 2.78 in. |
| May | 39.4 °F | 63.0 °F | 3.58 in. |
| June | 44.9 °F | 69.7 °F | 3.05 in. |
| July | 50.5 °F | 81.5 °F | 1.26 in. |
| August | 49.7 °F | 83.0 °F | 1.11 in. |
| September | 43.1 °F | 72.8 °F | 1.22 in. |
| October | 35.1 °F | 58.3 °F | 1.82 in. |
| November | 28.0 °F | 44.0 °F | 2.0 in. |
| December | 22.5 °F | 36.0 °F | 1.61 in. |
| Annual | 35.2 °F | 57.5 °F | 23.59 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | Jun. 1 - Jun. 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |