Groton, South Dakota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.2 °C (low) to 12.5 °C (high). Annual precipitation averages 583.7 Millimeters. Groton is located in USDA Plant Hardiness Zone 4a. 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 | -16.7 °C | -5.9 °C | 15.24 mm |
| February | -14.1 °C | -2.8 °C | 16.26 mm |
| March | -7.2 °C | 4.3 °C | 25.4 mm |
| April | -0.2 °C | 13.1 °C | 52.58 mm |
| May | 7.1 °C | 20.2 °C | 78.99 mm |
| June | 13.1 °C | 25.6 °C | 99.82 mm |
| July | 15.6 °C | 28.3 °C | 91.95 mm |
| August | 14 °C | 27.6 °C | 57.15 mm |
| September | 8.8 °C | 23.1 °C | 54.1 mm |
| October | 1.2 °C | 14.7 °C | 56.13 mm |
| November | -6.4 °C | 5.1 °C | 19.56 mm |
| December | -13.1 °C | -2.8 °C | 16.51 mm |
| Annual | 0.2 °C | 12.5 °C | 583.69 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 4a : -34.4°C to -31.7°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |