Ethan, South Dakota has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2.2 °C (low) to 14.6 °C (high). Annual precipitation averages 642.4 Millimeters. Ethan is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -13.2 °C | -2.5 °C | 12.95 mm |
| February | -10.9 °C | 0.6 °C | 19.56 mm |
| March | -5.1 °C | 7.1 °C | 29.72 mm |
| April | 1.5 °C | 14.8 °C | 74.42 mm |
| May | 8.4 °C | 21.3 °C | 91.69 mm |
| June | 14.7 °C | 27.1 °C | 96.52 mm |
| July | 17 °C | 30 °C | 77.72 mm |
| August | 15.7 °C | 28.8 °C | 74.68 mm |
| September | 10.5 °C | 24.7 °C | 69.85 mm |
| October | 2.9 °C | 16.5 °C | 53.85 mm |
| November | -4.6 °C | 7.4 °C | 23.62 mm |
| December | -10.6 °C | -0.2 °C | 17.78 mm |
| Annual | 2.2 °C | 14.6 °C | 642.36 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |