Ideal, South Dakota has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2.3 °C (low) to 15.7 °C (high). Annual precipitation averages 579.9 Millimeters. Ideal 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 | -11.7 °C | -0.1 °C | 12.7 mm |
| February | -9.8 °C | 2.4 °C | 16.26 mm |
| March | -4.8 °C | 8.7 °C | 26.92 mm |
| April | 1.1 °C | 15.1 °C | 68.07 mm |
| May | 7.6 °C | 21.1 °C | 88.9 mm |
| June | 13.6 °C | 26.9 °C | 98.04 mm |
| July | 16.7 °C | 31.3 °C | 68.58 mm |
| August | 15.6 °C | 30.3 °C | 64.01 mm |
| September | 10.4 °C | 25.7 °C | 54.61 mm |
| October | 2.9 °C | 17.4 °C | 47.75 mm |
| November | -4.2 °C | 8.5 °C | 19.05 mm |
| December | -9.6 °C | 1.6 °C | 14.99 mm |
| Annual | 2.3 °C | 15.7 °C | 579.88 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 | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |