Prairie du Sac, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.5 °C (low) to 13.8 °C (high). Annual precipitation averages 920.5 Millimeters. Prairie du Sac is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -12.3 °C | -2.7 °C | 33.02 mm |
| February | -11.1 °C | -0.2 °C | 33.27 mm |
| March | -4.8 °C | 6.3 °C | 50.8 mm |
| April | 1.6 °C | 13.9 °C | 95.5 mm |
| May | 8.2 °C | 20.7 °C | 106.68 mm |
| June | 14.2 °C | 26.1 °C | 138.68 mm |
| July | 16.2 °C | 28.1 °C | 110.74 mm |
| August | 14.9 °C | 27.1 °C | 106.17 mm |
| September | 10.4 °C | 23.1 °C | 87.63 mm |
| October | 3.8 °C | 15.9 °C | 68.33 mm |
| November | -2.6 °C | 7.4 °C | 51.05 mm |
| December | -8.4 °C | 0.4 °C | 38.61 mm |
| Annual | 2.5 °C | 13.8 °C | 920.48 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| 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 | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |