Riggins, Idaho has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.9 °C (low) to 18.1 °C (high). Annual precipitation averages 460 Millimeters. Riggins is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.9 °C | 4.9 °C | 32.77 mm |
| February | -2.2 °C | 7.9 °C | 31.5 mm |
| March | 0.4 °C | 12.5 °C | 50.04 mm |
| April | 2.8 °C | 17.3 °C | 52.32 mm |
| May | 6.4 °C | 22.3 °C | 65.02 mm |
| June | 9.6 °C | 26.4 °C | 47.75 mm |
| July | 12.7 °C | 33.1 °C | 19.81 mm |
| August | 12.2 °C | 33.2 °C | 19.3 mm |
| September | 8.2 °C | 27.3 °C | 25.91 mm |
| October | 3.5 °C | 18.4 °C | 35.81 mm |
| November | -0.3 °C | 9.4 °C | 39.12 mm |
| December | -3.1 °C | 4.4 °C | 40.64 mm |
| Annual | 3.9 °C | 18.1 °C | 459.99 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |