Millston, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.7 °C (low) to 13.1 °C (high). Annual precipitation averages 919.7 Millimeters. Millston 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 | -14.8 °C | -3.8 °C | 29.97 mm |
| February | -13.2 °C | -1 °C | 28.19 mm |
| March | -6.6 °C | 5.7 °C | 46.48 mm |
| April | 0.1 °C | 13.4 °C | 90.93 mm |
| May | 6.9 °C | 20.3 °C | 114.55 mm |
| June | 12.3 °C | 25.4 °C | 136.14 mm |
| July | 14.5 °C | 27.6 °C | 107.19 mm |
| August | 13.3 °C | 26.4 °C | 112.27 mm |
| September | 8.6 °C | 22.4 °C | 95.76 mm |
| October | 2.1 °C | 15 °C | 73.66 mm |
| November | -4.2 °C | 6.3 °C | 46.48 mm |
| December | -10.6 °C | -0.9 °C | 38.1 mm |
| Annual | 0.7 °C | 13.1 °C | 919.72 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 | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |