Delmont, South Dakota has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2.8 °C (low) to 15.7 °C (high). Annual precipitation averages 654.1 Millimeters. Delmont is located in USDA Plant Hardiness Zone 5a. 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 | -11.9 °C | -0.5 °C | 14.48 mm |
| February | -9.8 °C | 2.3 °C | 19.81 mm |
| March | -4.2 °C | 8.9 °C | 31.75 mm |
| April | 1.8 °C | 15.4 °C | 75.95 mm |
| May | 8.7 °C | 21.9 °C | 95 mm |
| June | 14.7 °C | 27.6 °C | 96.52 mm |
| July | 17.4 °C | 30.8 °C | 76.71 mm |
| August | 16.2 °C | 29.6 °C | 75.95 mm |
| September | 10.9 °C | 25.4 °C | 69.85 mm |
| October | 3.5 °C | 17.1 °C | 56.13 mm |
| November | -3.8 °C | 8.6 °C | 23.37 mm |
| December | -9.5 °C | 1.2 °C | 18.54 mm |
| Annual | 2.8 °C | 15.7 °C | 654.06 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 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |