Portage, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41.9 °F (low) to 59.5 °F (high). Annual precipitation averages 40 Inches. 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 | 18.3 °F | 32.6 °F | 2.44 in. |
| February | 20.8 °F | 36.3 °F | 2.14 in. |
| March | 29.3 °F | 46.5 °F | 2.31 in. |
| April | 39.2 °F | 58.9 °F | 3.59 in. |
| May | 49.7 °F | 69.7 °F | 4.12 in. |
| June | 59.6 °F | 79.2 °F | 4.64 in. |
| July | 64.4 °F | 83.0 °F | 4.18 in. |
| August | 63.2 °F | 81.5 °F | 4.02 in. |
| September | 55.7 °F | 75.9 °F | 3.48 in. |
| October | 44.3 °F | 63.6 °F | 3.98 in. |
| November | 34.1 °F | 49.5 °F | 2.84 in. |
| December | 24.2 °F | 37.7 °F | 2.27 in. |
| Annual | 41.9 °F | 59.5 °F | 40.01 in. |
| 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 : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |