Ethan, South Dakota has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 36 °F (low) to 58.3 °F (high). Annual precipitation averages 25.3 Inches. 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 | 8.2 °F | 27.5 °F | 0.51 in. |
| February | 12.4 °F | 33.0 °F | 0.77 in. |
| March | 22.9 °F | 44.7 °F | 1.17 in. |
| April | 34.7 °F | 58.6 °F | 2.93 in. |
| May | 47.2 °F | 70.4 °F | 3.61 in. |
| June | 58.4 °F | 80.7 °F | 3.8 in. |
| July | 62.6 °F | 86.0 °F | 3.06 in. |
| August | 60.2 °F | 83.8 °F | 2.94 in. |
| September | 50.9 °F | 76.5 °F | 2.75 in. |
| October | 37.2 °F | 61.7 °F | 2.12 in. |
| November | 23.8 °F | 45.3 °F | 0.93 in. |
| December | 13.0 °F | 31.7 °F | 0.7 in. |
| Annual | 36 °F | 58.3 °F | 25.29 in. |
| 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 : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |