Portage, Michigan has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39.7 °F (low) to 58.6 °F (high). Annual precipitation averages 39.7 Inches. Portage is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 17.5 °F | 31.3 °F | 2.93 in. |
| February | 18.5 °F | 34.3 °F | 2.15 in. |
| March | 26.3 °F | 45.0 °F | 2.37 in. |
| April | 37.4 °F | 58.8 °F | 3.51 in. |
| May | 48.9 °F | 70.0 °F | 4.25 in. |
| June | 58.1 °F | 79.2 °F | 4.08 in. |
| July | 61.5 °F | 83.0 °F | 3.53 in. |
| August | 59.8 °F | 81.1 °F | 4.14 in. |
| September | 52.3 °F | 74.7 °F | 3.48 in. |
| October | 41.3 °F | 61.6 °F | 3.83 in. |
| November | 31.9 °F | 47.9 °F | 2.93 in. |
| December | 23.4 °F | 36.2 °F | 2.46 in. |
| Annual | 39.7 °F | 58.6 °F | 39.66 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |