De Smet, South Dakota has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 34.2 °F (low) to 54.8 °F (high). Annual precipitation averages 25.3 Inches. De Smet is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 5.1 °F | 23.3 °F | 0.57 in. |
| February | 9.3 °F | 28.5 °F | 0.68 in. |
| March | 20.8 °F | 40.5 °F | 1.12 in. |
| April | 33.1 °F | 55.4 °F | 2.4 in. |
| May | 45.6 °F | 67.7 °F | 3.37 in. |
| June | 56.6 °F | 77.5 °F | 4.43 in. |
| July | 61.1 °F | 82.5 °F | 3.5 in. |
| August | 58.6 °F | 80.2 °F | 2.92 in. |
| September | 49.9 °F | 72.9 °F | 2.75 in. |
| October | 36.2 °F | 58.4 °F | 2.12 in. |
| November | 22.6 °F | 41.9 °F | 0.79 in. |
| December | 11.0 °F | 28.2 °F | 0.67 in. |
| Annual | 34.2 °F | 54.8 °F | 25.32 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |