Sparta, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.5 °C (low) to 13.4 °C (high). Annual precipitation averages 907.8 Millimeters. Sparta 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 | -13.8 °C | -3.4 °C | 27.43 mm |
| February | -12.1 °C | -0.8 °C | 28.45 mm |
| March | -5.6 °C | 5.9 °C | 45.47 mm |
| April | 1.1 °C | 13.6 °C | 93.22 mm |
| May | 7.6 °C | 20.6 °C | 117.35 mm |
| June | 13.2 °C | 25.9 °C | 138.18 mm |
| July | 15.3 °C | 28 °C | 106.68 mm |
| August | 14 °C | 26.8 °C | 108.97 mm |
| September | 9.2 °C | 22.6 °C | 95.5 mm |
| October | 2.8 °C | 15.2 °C | 65.79 mm |
| November | -3.4 °C | 6.6 °C | 43.94 mm |
| December | -9.8 °C | -0.6 °C | 36.83 mm |
| Annual | 1.5 °C | 13.4 °C | 907.81 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 | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |