De Smet, Idaho has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 2 °C (low) to 14.9 °C (high). Annual precipitation averages 633 Millimeters. 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 | -3.8 °C | 2.9 °C | 89.66 mm |
| February | -3.3 °C | 5.3 °C | 65.28 mm |
| March | -1.3 °C | 9.3 °C | 65.28 mm |
| April | 1.3 °C | 13.8 °C | 51.56 mm |
| May | 4.5 °C | 19.1 °C | 58.67 mm |
| June | 7.4 °C | 22.1 °C | 40.39 mm |
| July | 9.3 °C | 28.3 °C | 15.24 mm |
| August | 8.9 °C | 29.2 °C | 15.75 mm |
| September | 5.3 °C | 23.9 °C | 19.3 mm |
| October | 1.3 °C | 15.8 °C | 51.05 mm |
| November | -1.5 °C | 7.1 °C | 75.18 mm |
| December | -4.5 °C | 2.3 °C | 85.6 mm |
| Annual | 2 °C | 14.9 °C | 632.96 mm |
| 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 : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |