Isabel, South Dakota has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 0.6 °C (low) to 13.9 °C (high). Annual precipitation averages 457.9 Millimeters. 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 | -13.4 °C | -2.3 °C | 10.92 mm |
| February | -11.6 °C | -0.2 °C | 13.72 mm |
| March | -6.4 °C | 6.2 °C | 24.38 mm |
| April | -0.5 °C | 13.4 °C | 40.89 mm |
| May | 6 °C | 19.6 °C | 68.83 mm |
| June | 11.8 °C | 25.3 °C | 85.09 mm |
| July | 15 °C | 29.8 °C | 67.31 mm |
| August | 13.8 °C | 29.5 °C | 44.7 mm |
| September | 8.4 °C | 24.3 °C | 34.8 mm |
| October | 1.1 °C | 15 °C | 44.7 mm |
| November | -6.1 °C | 6.4 °C | 10.92 mm |
| December | -11.4 °C | -0.3 °C | 11.68 mm |
| Annual | 0.6 °C | 13.9 °C | 457.94 mm |
| 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 : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |