Gillett, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.8 °C (low) to 12.6 °C (high). Annual precipitation averages 858 Millimeters. Gillett 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 | -13.9 °C | -3.8 °C | 35.56 mm |
| February | -13.1 °C | -1.7 °C | 30.23 mm |
| March | -7.1 °C | 4.7 °C | 45.97 mm |
| April | -0.3 °C | 12.4 °C | 84.07 mm |
| May | 6.4 °C | 19.7 °C | 94.23 mm |
| June | 12 °C | 24.7 °C | 119.38 mm |
| July | 14.3 °C | 27.2 °C | 96.27 mm |
| August | 13.3 °C | 26.1 °C | 92.71 mm |
| September | 8.7 °C | 22 °C | 91.19 mm |
| October | 2.3 °C | 14.3 °C | 77.22 mm |
| November | -3.4 °C | 6.1 °C | 47.5 mm |
| December | -9.8 °C | -1.1 °C | 43.69 mm |
| Annual | 0.8 °C | 12.6 °C | 858.02 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 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |