Interior, South Dakota has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 35.8 °F (low) to 62.5 °F (high). Annual precipitation averages 19.3 Inches. Interior is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 12.5 °F | 35.5 °F | 0.43 in. |
| February | 15.0 °F | 39.1 °F | 0.55 in. |
| March | 23.9 °F | 50.0 °F | 1.12 in. |
| April | 33.5 °F | 61.0 °F | 2.28 in. |
| May | 44.9 °F | 71.0 °F | 3.46 in. |
| June | 55.3 °F | 81.5 °F | 3.43 in. |
| July | 61.8 °F | 90.0 °F | 2.35 in. |
| August | 59.4 °F | 89.7 °F | 1.73 in. |
| September | 49.3 °F | 80.8 °F | 1.32 in. |
| October | 36.2 °F | 65.0 °F | 1.6 in. |
| November | 23.4 °F | 48.8 °F | 0.55 in. |
| December | 14.6 °F | 37.3 °F | 0.49 in. |
| Annual | 35.8 °F | 62.5 °F | 19.31 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |