Eureka, South Dakota has a Humid Continental Mild Summer With Dry Winters climate (Köppen classification: Dwb). Average annual temperatures range from -0.2 °C (low) to 11.9 °C (high). Annual precipitation averages 502.4 Millimeters. Eureka 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 | -16.2 °C | -6.1 °C | 9.91 mm |
| February | -13.8 °C | -3.4 °C | 13.21 mm |
| March | -7.7 °C | 3.6 °C | 20.32 mm |
| April | -0.9 °C | 12.4 °C | 40.13 mm |
| May | 6.1 °C | 19.3 °C | 78.49 mm |
| June | 12.1 °C | 24.6 °C | 86.11 mm |
| July | 14.9 °C | 28.1 °C | 81.03 mm |
| August | 13.6 °C | 27.4 °C | 56.39 mm |
| September | 8.3 °C | 22.5 °C | 46.99 mm |
| October | 0.9 °C | 13.6 °C | 43.18 mm |
| November | -6.7 °C | 4.4 °C | 14.22 mm |
| December | -12.7 °C | -3.1 °C | 12.45 mm |
| Annual | -0.2 °C | 11.9 °C | 502.43 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 | Dwb - Humid Continental Mild Summer With Dry Winters |