Donnelly, Idaho has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from -2.5 °C (low) to 12.8 °C (high). Annual precipitation averages 644.9 Millimeters. Donnelly is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Jun. 1 - Jun. 10 through the first frost around Aug. 21 - Aug. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.2 °C | 0.2 °C | 77.72 mm |
| February | -10.2 °C | 2.7 °C | 62.23 mm |
| March | -6.7 °C | 6.6 °C | 72.39 mm |
| April | -3.1 °C | 10.9 °C | 62.74 mm |
| May | 1.1 °C | 16.4 °C | 61.72 mm |
| June | 4.1 °C | 20.9 °C | 46.23 mm |
| July | 7.1 °C | 27.7 °C | 13.46 mm |
| August | 6.1 °C | 27.6 °C | 11.94 mm |
| September | 1.8 °C | 22.1 °C | 24.38 mm |
| October | -2.4 °C | 13.9 °C | 46.48 mm |
| November | -6.3 °C | 5.2 °C | 68.58 mm |
| December | -10.7 °C | -0.2 °C | 97.03 mm |
| Annual | -2.5 °C | 12.8 °C | 644.9 mm |
| Average First Frost Date | Aug. 21 - Aug. 31 |
| Average Last Frost Date | Jun. 1 - Jun. 10 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |