Winner, South Dakota has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2.6 °C (low) to 15.8 °C (high). Annual precipitation averages 578.9 Millimeters. Winner is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.2 °C | 0.4 °C | 13.46 mm |
| February | -9.3 °C | 2.8 °C | 14.99 mm |
| March | -4.5 °C | 8.8 °C | 27.43 mm |
| April | 1.2 °C | 15 °C | 70.36 mm |
| May | 7.7 °C | 20.9 °C | 89.41 mm |
| June | 13.7 °C | 26.8 °C | 100.33 mm |
| July | 16.8 °C | 31.2 °C | 63.5 mm |
| August | 15.7 °C | 30.3 °C | 60.2 mm |
| September | 10.6 °C | 25.7 °C | 52.32 mm |
| October | 3.1 °C | 17.4 °C | 51.31 mm |
| November | -3.9 °C | 8.6 °C | 20.07 mm |
| December | -9.2 °C | 2 °C | 15.49 mm |
| Annual | 2.6 °C | 15.8 °C | 578.87 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°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 |