Ketchum, Idaho has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 26.4 °F (low) to 55.5 °F (high). Annual precipitation averages 18.1 Inches. Ketchum is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Jun. 11 - Jun. 20 through the first frost around Aug. 21 - Aug. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.6 °F | 31.6 °F | 2.32 in. |
| February | 10.4 °F | 35.8 °F | 1.75 in. |
| March | 18.1 °F | 43.7 °F | 1.83 in. |
| April | 26.1 °F | 52.8 °F | 1.2 in. |
| May | 33.8 °F | 62.5 °F | 1.79 in. |
| June | 39.0 °F | 71.3 °F | 1.46 in. |
| July | 45.4 °F | 82.7 °F | 0.46 in. |
| August | 43.9 °F | 81.7 °F | 0.62 in. |
| September | 36.9 °F | 72.0 °F | 0.86 in. |
| October | 28.0 °F | 58.1 °F | 1.43 in. |
| November | 17.9 °F | 42.4 °F | 1.53 in. |
| December | 9.1 °F | 31.3 °F | 2.84 in. |
| Annual | 26.4 °F | 55.5 °F | 18.09 in. |
| Average First Frost Date | Aug. 21 - Aug. 31 |
| Average Last Frost Date | Jun. 11 - Jun. 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |