Rockham, South Dakota has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 32.9 °F (low) to 55.5 °F (high). Annual precipitation averages 22.1 Inches. Rockham 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 | 3.7 °F | 23.2 °F | 0.41 in. |
| February | 7.8 °F | 28.4 °F | 0.68 in. |
| March | 19.7 °F | 41.1 °F | 0.99 in. |
| April | 31.7 °F | 56.1 °F | 2.1 in. |
| May | 44.7 °F | 68.6 °F | 3.22 in. |
| June | 55.6 °F | 78.4 °F | 3.64 in. |
| July | 60.4 °F | 84.2 °F | 3.35 in. |
| August | 57.7 °F | 82.6 °F | 2.38 in. |
| September | 48.1 °F | 74.3 °F | 2.17 in. |
| October | 34.5 °F | 58.9 °F | 1.91 in. |
| November | 20.9 °F | 42.4 °F | 0.67 in. |
| December | 9.6 °F | 28.3 °F | 0.54 in. |
| Annual | 32.9 °F | 55.5 °F | 22.06 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 4a : -30°F to -25°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |