Gregory, South Dakota has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2.3 °C (low) to 15.5 °C (high). Annual precipitation averages 665.5 Millimeters. Gregory is located in USDA Plant Hardiness Zone 5a. 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 | -11.3 °C | 0.4 °C | 12.95 mm |
| February | -9.6 °C | 2.8 °C | 18.8 mm |
| March | -4.7 °C | 8.7 °C | 30.73 mm |
| April | 1.1 °C | 14.4 °C | 73.91 mm |
| May | 7.4 °C | 20.7 °C | 103.63 mm |
| June | 13.5 °C | 26.6 °C | 111.51 mm |
| July | 16.6 °C | 30.6 °C | 74.42 mm |
| August | 15.3 °C | 29.4 °C | 81.79 mm |
| September | 10.2 °C | 24.9 °C | 63.75 mm |
| October | 2.5 °C | 16.8 °C | 57.91 mm |
| November | -4.4 °C | 8.4 °C | 19.05 mm |
| December | -9.5 °C | 1.8 °C | 17.02 mm |
| Annual | 2.3 °C | 15.5 °C | 665.47 mm |
| 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 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |