Morristown, South Dakota has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from -0.4 °C (low) to 13.4 °C (high). Annual precipitation averages 449.1 Millimeters. 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 | -14.7 °C | -3.4 °C | 8.38 mm |
| February | -12.7 °C | -1.2 °C | 12.19 mm |
| March | -7.2 °C | 5.4 °C | 19.05 mm |
| April | -1.2 °C | 13.2 °C | 34.8 mm |
| May | 5.3 °C | 19.6 °C | 70.87 mm |
| June | 11 °C | 25.1 °C | 80.77 mm |
| July | 14 °C | 29.4 °C | 75.18 mm |
| August | 12.8 °C | 29.2 °C | 47.5 mm |
| September | 7.4 °C | 23.8 °C | 37.34 mm |
| October | 0.2 °C | 14.7 °C | 36.83 mm |
| November | -6.9 °C | 5.7 °C | 15.49 mm |
| December | -12.6 °C | -1.1 °C | 10.67 mm |
| Annual | -0.4 °C | 13.4 °C | 449.07 mm |
| 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 : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |