Morristown, South Dakota has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 31.3 °F (low) to 56 °F (high). Annual precipitation averages 17.7 Inches. Morristown is located in USDA Plant Hardiness Zone 4b. 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 | 5.6 °F | 25.9 °F | 0.33 in. |
| February | 9.1 °F | 29.9 °F | 0.48 in. |
| March | 19.1 °F | 41.7 °F | 0.75 in. |
| April | 29.8 °F | 55.7 °F | 1.37 in. |
| May | 41.6 °F | 67.3 °F | 2.79 in. |
| June | 51.8 °F | 77.1 °F | 3.18 in. |
| July | 57.2 °F | 84.9 °F | 2.96 in. |
| August | 55.1 °F | 84.5 °F | 1.87 in. |
| September | 45.4 °F | 74.9 °F | 1.47 in. |
| October | 32.4 °F | 58.4 °F | 1.45 in. |
| November | 19.5 °F | 42.2 °F | 0.61 in. |
| December | 9.4 °F | 30.0 °F | 0.42 in. |
| Annual | 31.3 °F | 56 °F | 17.68 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4a : -30°F to -25°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |