Isabel, South Dakota has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 33 °F (low) to 57 °F (high). Annual precipitation averages 18 Inches. Isabel 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 Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.9 °F | 27.9 °F | 0.43 in. |
| February | 11.1 °F | 31.6 °F | 0.54 in. |
| March | 20.5 °F | 43.2 °F | 0.96 in. |
| April | 31.1 °F | 56.1 °F | 1.61 in. |
| May | 42.8 °F | 67.2 °F | 2.71 in. |
| June | 53.2 °F | 77.6 °F | 3.35 in. |
| July | 59.0 °F | 85.7 °F | 2.65 in. |
| August | 56.8 °F | 85.1 °F | 1.76 in. |
| September | 47.1 °F | 75.7 °F | 1.37 in. |
| October | 33.9 °F | 59.0 °F | 1.76 in. |
| November | 21.1 °F | 43.5 °F | 0.43 in. |
| December | 11.4 °F | 31.4 °F | 0.46 in. |
| Annual | 33 °F | 57 °F | 18.03 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| 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 4b : -25°F to -20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |