Challis, Idaho has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from -0.7 °C (low) to 14 °C (high). Annual precipitation averages 184.7 Millimeters. Challis is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Aug. 11 - Aug. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.6 °C | -0.4 °C | 11.94 mm |
| February | -9.2 °C | 2.9 °C | 7.11 mm |
| March | -4.7 °C | 8.6 °C | 13.46 mm |
| April | -1.1 °C | 13.1 °C | 16.51 mm |
| May | 3.3 °C | 18.6 °C | 26.42 mm |
| June | 7.1 °C | 23.3 °C | 26.42 mm |
| July | 10.7 °C | 29.7 °C | 11.94 mm |
| August | 9.4 °C | 28.7 °C | 14.22 mm |
| September | 5.2 °C | 23.2 °C | 16.51 mm |
| October | -0.3 °C | 14.9 °C | 13.97 mm |
| November | -6.2 °C | 5.8 °C | 12.19 mm |
| December | -11.2 °C | -0.7 °C | 13.97 mm |
| Annual | -0.7 °C | 14 °C | 184.66 mm |
| Average First Frost Date | Aug. 11 - Aug. 20 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |