De Smet, Idaho has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 35.6 °F (low) to 58.9 °F (high). Annual precipitation averages 24.9 Inches. De Smet is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 25.1 °F | 37.3 °F | 3.53 in. |
| February | 26.0 °F | 41.5 °F | 2.57 in. |
| March | 29.7 °F | 48.8 °F | 2.57 in. |
| April | 34.3 °F | 56.8 °F | 2.03 in. |
| May | 40.1 °F | 66.3 °F | 2.31 in. |
| June | 45.4 °F | 71.8 °F | 1.59 in. |
| July | 48.8 °F | 83.0 °F | 0.6 in. |
| August | 48.1 °F | 84.5 °F | 0.62 in. |
| September | 41.6 °F | 75.1 °F | 0.76 in. |
| October | 34.4 °F | 60.5 °F | 2.01 in. |
| November | 29.3 °F | 44.8 °F | 2.96 in. |
| December | 23.9 °F | 36.1 °F | 3.37 in. |
| Annual | 35.6 °F | 58.9 °F | 24.92 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |