Boulder Junction, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 29.7 °F (low) to 50.6 °F (high). Annual precipitation averages 32.8 Inches. 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 | 2.6 °F | 21.1 °F | 1.27 in. |
| February | 3.2 °F | 25.7 °F | 1.12 in. |
| March | 13.0 °F | 37.0 °F | 1.59 in. |
| April | 26.5 °F | 49.6 °F | 2.73 in. |
| May | 40.5 °F | 64.1 °F | 3.57 in. |
| June | 50.7 °F | 73.2 °F | 4.36 in. |
| July | 55.0 °F | 77.0 °F | 4.02 in. |
| August | 52.9 °F | 75.0 °F | 3.55 in. |
| September | 45.4 °F | 67.1 °F | 3.62 in. |
| October | 33.6 °F | 52.9 °F | 3.51 in. |
| November | 22.4 °F | 37.9 °F | 1.92 in. |
| December | 10.0 °F | 26.0 °F | 1.57 in. |
| Annual | 29.7 °F | 50.6 °F | 32.83 in. |
| 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 : -30°F to -25°F |
| Plant Hardiness Zone - 2012 | Zone 4a : -30°F to -25°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |