Lennox, South Dakota has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2 °C (low) to 13.9 °C (high). Annual precipitation averages 702.3 Millimeters. Lennox 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 | -13.8 °C | -3.4 °C | 14.99 mm |
| February | -11.4 °C | -0.7 °C | 19.56 mm |
| March | -5.1 °C | 6.3 °C | 36.07 mm |
| April | 1.3 °C | 14.3 °C | 74.17 mm |
| May | 8.4 °C | 21.2 °C | 97.28 mm |
| June | 14.8 °C | 26.8 °C | 111 mm |
| July | 16.8 °C | 29.1 °C | 83.57 mm |
| August | 15.3 °C | 27.6 °C | 82.8 mm |
| September | 10.3 °C | 23.8 °C | 71.88 mm |
| October | 2.8 °C | 16.1 °C | 60.2 mm |
| November | -4.7 °C | 6.8 °C | 29.46 mm |
| December | -10.8 °C | -0.9 °C | 21.34 mm |
| Annual | 2 °C | 13.9 °C | 702.32 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 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |