Hermosa, South Dakota has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 35.8 °F (low) to 59.3 °F (high). Annual precipitation averages 18 Inches. Hermosa 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 | 15.0 °F | 37.0 °F | 0.25 in. |
| February | 16.2 °F | 38.5 °F | 0.44 in. |
| March | 24.2 °F | 48.0 °F | 0.75 in. |
| April | 32.6 °F | 55.7 °F | 1.99 in. |
| May | 43.2 °F | 64.9 °F | 3.36 in. |
| June | 53.3 °F | 76.5 °F | 3.38 in. |
| July | 60.0 °F | 85.0 °F | 2.42 in. |
| August | 58.0 °F | 83.9 °F | 1.97 in. |
| September | 48.7 °F | 75.1 °F | 1.48 in. |
| October | 36.2 °F | 60.6 °F | 1.29 in. |
| November | 25.6 °F | 48.1 °F | 0.39 in. |
| December | 16.9 °F | 38.3 °F | 0.31 in. |
| Annual | 35.8 °F | 59.3 °F | 18.03 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 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 | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |