Onaka, South Dakota has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 0.3 °C (low) to 12.8 °C (high). Annual precipitation averages 505.2 Millimeters. Onaka is located in USDA Plant Hardiness Zone 4b. 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 | -15.2 °C | -4.8 °C | 9.65 mm |
| February | -13.1 °C | -2.2 °C | 13.46 mm |
| March | -7.1 °C | 4.7 °C | 20.07 mm |
| April | -0.6 °C | 13 °C | 43.43 mm |
| May | 6.3 °C | 19.9 °C | 75.95 mm |
| June | 12.4 °C | 25.3 °C | 89.92 mm |
| July | 15.1 °C | 28.8 °C | 73.91 mm |
| August | 14 °C | 28.2 °C | 59.18 mm |
| September | 8.7 °C | 23.3 °C | 51.82 mm |
| October | 1.3 °C | 14.5 °C | 41.4 mm |
| November | -6 °C | 5.3 °C | 14.48 mm |
| December | -12 °C | -2.2 °C | 11.94 mm |
| Annual | 0.3 °C | 12.8 °C | 505.21 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 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |