Portage, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.5 °C (low) to 15.3 °C (high). Annual precipitation averages 1016.3 Millimeters. Portage is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.6 °C | 0.3 °C | 61.98 mm |
| February | -6.2 °C | 2.4 °C | 54.36 mm |
| March | -1.5 °C | 8.1 °C | 58.67 mm |
| April | 4 °C | 14.9 °C | 91.19 mm |
| May | 9.8 °C | 20.9 °C | 104.65 mm |
| June | 15.3 °C | 26.2 °C | 117.86 mm |
| July | 18 °C | 28.3 °C | 106.17 mm |
| August | 17.3 °C | 27.5 °C | 102.11 mm |
| September | 13.2 °C | 24.4 °C | 88.39 mm |
| October | 6.8 °C | 17.6 °C | 101.09 mm |
| November | 1.2 °C | 9.7 °C | 72.14 mm |
| December | -4.3 °C | 3.2 °C | 57.66 mm |
| Annual | 5.5 °C | 15.3 °C | 1016.27 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |