Boulder Junction, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -1.3 °C (low) to 10.3 °C (high). Annual precipitation averages 833.9 Millimeters. Boulder Junction is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -16.3 °C | -6.1 °C | 32.26 mm |
| February | -16 °C | -3.5 °C | 28.45 mm |
| March | -10.6 °C | 2.8 °C | 40.39 mm |
| April | -3.1 °C | 9.8 °C | 69.34 mm |
| May | 4.7 °C | 17.8 °C | 90.68 mm |
| June | 10.4 °C | 22.9 °C | 110.74 mm |
| July | 12.8 °C | 25 °C | 102.11 mm |
| August | 11.6 °C | 23.9 °C | 90.17 mm |
| September | 7.4 °C | 19.5 °C | 91.95 mm |
| October | 0.9 °C | 11.6 °C | 89.15 mm |
| November | -5.3 °C | 3.3 °C | 48.77 mm |
| December | -12.2 °C | -3.3 °C | 39.88 mm |
| Annual | -1.3 °C | 10.3 °C | 833.89 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4a : -34.4°C to -31.7°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |