Portage, Michigan has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.3 °C (low) to 14.8 °C (high). Annual precipitation averages 1007.4 Millimeters. 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 | -8.1 °C | -0.4 °C | 74.42 mm |
| February | -7.5 °C | 1.3 °C | 54.61 mm |
| March | -3.2 °C | 7.2 °C | 60.2 mm |
| April | 3 °C | 14.9 °C | 89.15 mm |
| May | 9.4 °C | 21.1 °C | 107.95 mm |
| June | 14.5 °C | 26.2 °C | 103.63 mm |
| July | 16.4 °C | 28.3 °C | 89.66 mm |
| August | 15.4 °C | 27.3 °C | 105.16 mm |
| September | 11.3 °C | 23.7 °C | 88.39 mm |
| October | 5.2 °C | 16.4 °C | 97.28 mm |
| November | -0.1 °C | 8.8 °C | 74.42 mm |
| December | -4.8 °C | 2.3 °C | 62.48 mm |
| Annual | 4.3 °C | 14.8 °C | 1007.35 mm |
| 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 : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |