Portage, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 36.2 °F (low) to 56.6 °F (high). Annual precipitation averages 37.4 Inches. Portage is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 9.4 °F | 26.9 °F | 1.41 in. |
| February | 12.1 °F | 31.4 °F | 1.38 in. |
| March | 22.8 °F | 43.3 °F | 2.08 in. |
| April | 34.5 °F | 56.7 °F | 4.01 in. |
| May | 46.8 °F | 69.1 °F | 4.46 in. |
| June | 57.0 °F | 78.6 °F | 5.52 in. |
| July | 60.9 °F | 82.3 °F | 4.22 in. |
| August | 58.5 °F | 80.5 °F | 4.09 in. |
| September | 50.3 °F | 73.1 °F | 3.54 in. |
| October | 38.6 °F | 59.8 °F | 2.88 in. |
| November | 27.4 °F | 44.9 °F | 2.12 in. |
| December | 16.6 °F | 32.3 °F | 1.7 in. |
| Annual | 36.2 °F | 56.6 °F | 37.41 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |