Grangeville, Idaho has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.8 °C (low) to 14.1 °C (high). Annual precipitation averages 599.2 Millimeters. 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 | -4.8 °C | 2.9 °C | 30.48 mm |
| February | -4.1 °C | 4.9 °C | 36.83 mm |
| March | -1.9 °C | 8.9 °C | 63.75 mm |
| April | 0.6 °C | 12.8 °C | 70.61 mm |
| May | 4.1 °C | 17.2 °C | 90.93 mm |
| June | 7.2 °C | 20.9 °C | 77.47 mm |
| July | 10.3 °C | 27.5 °C | 32 mm |
| August | 9.8 °C | 28.3 °C | 28.19 mm |
| September | 6.2 °C | 22.7 °C | 30.99 mm |
| October | 1.7 °C | 14.6 °C | 46.23 mm |
| November | -2.2 °C | 6.7 °C | 50.8 mm |
| December | -5.3 °C | 2.2 °C | 40.89 mm |
| Annual | 1.8 °C | 14.1 °C | 599.17 mm |
| 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 : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |