Oldham, South Dakota has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 1.2 °C (low) to 12.7 °C (high). Annual precipitation averages 655.6 Millimeters. Oldham 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 Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -14.8 °C | -4.7 °C | 14.48 mm |
| February | -12.4 °C | -1.9 °C | 18.03 mm |
| March | -6.1 °C | 4.8 °C | 29.97 mm |
| April | 0.7 °C | 13.1 °C | 66.04 mm |
| May | 7.7 °C | 20 °C | 92.71 mm |
| June | 13.7 °C | 25.4 °C | 104.14 mm |
| July | 16.1 °C | 28 °C | 83.82 mm |
| August | 14.7 °C | 26.7 °C | 78.49 mm |
| September | 9.8 °C | 22.8 °C | 71.63 mm |
| October | 2.3 °C | 14.9 °C | 54.1 mm |
| November | -5.2 °C | 5.6 °C | 23.88 mm |
| December | -11.6 °C | -1.9 °C | 18.29 mm |
| Annual | 1.2 °C | 12.7 °C | 655.58 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| 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 |