Selby, South Dakota has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 0.2 °C (low) to 12.6 °C (high). Annual precipitation averages 479.3 Millimeters. Selby 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 | -15.3 °C | -5 °C | 10.41 mm |
| February | -13.3 °C | -2.4 °C | 14.73 mm |
| March | -7.2 °C | 4.4 °C | 19.3 mm |
| April | -0.7 °C | 12.7 °C | 43.18 mm |
| May | 6.3 °C | 19.6 °C | 70.36 mm |
| June | 12.3 °C | 25.2 °C | 84.33 mm |
| July | 15.2 °C | 28.7 °C | 69.85 mm |
| August | 14 °C | 28.1 °C | 56.13 mm |
| September | 8.7 °C | 23 °C | 41.15 mm |
| October | 1.2 °C | 14.1 °C | 43.43 mm |
| November | -6.1 °C | 5.1 °C | 13.46 mm |
| December | -12.2 °C | -2.3 °C | 12.95 mm |
| Annual | 0.2 °C | 12.6 °C | 479.28 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 | Abnormally Dry |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |