Grenville, South Dakota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 33.3 °F (low) to 52.8 °F (high). Annual precipitation averages 23.3 Inches. Grenville 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 | 2.5 °F | 20.7 °F | 0.63 in. |
| February | 6.0 °F | 25.4 °F | 0.59 in. |
| March | 17.9 °F | 37.3 °F | 0.91 in. |
| April | 31.6 °F | 52.9 °F | 2.17 in. |
| May | 45.2 °F | 66.4 °F | 2.86 in. |
| June | 56.4 °F | 76.0 °F | 3.73 in. |
| July | 61.0 °F | 80.9 °F | 3.99 in. |
| August | 59.3 °F | 79.8 °F | 2.49 in. |
| September | 50.6 °F | 71.8 °F | 2.35 in. |
| October | 36.7 °F | 56.7 °F | 2.19 in. |
| November | 22.7 °F | 39.5 °F | 0.69 in. |
| December | 9.7 °F | 25.8 °F | 0.73 in. |
| Annual | 33.3 °F | 52.8 °F | 23.33 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 | Dfb - Humid Continental Mild Summer, Wet All Year |