Westport, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 43.4 °F (low) to 63.7 °F (high). Annual precipitation averages 47.7 Inches. Westport is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 21.6 °F | 37.9 °F | 3.42 in. |
| February | 23.9 °F | 42.1 °F | 2.87 in. |
| March | 32.2 °F | 52.5 °F | 3.96 in. |
| April | 42.4 °F | 65.0 °F | 4.99 in. |
| May | 53.0 °F | 74.2 °F | 5.19 in. |
| June | 61.4 °F | 81.9 °F | 5.18 in. |
| July | 64.7 °F | 84.9 °F | 4.32 in. |
| August | 62.9 °F | 84.1 °F | 3.71 in. |
| September | 55.3 °F | 78.7 °F | 3.33 in. |
| October | 43.8 °F | 67.0 °F | 3.41 in. |
| November | 33.8 °F | 53.5 °F | 3.67 in. |
| December | 26.1 °F | 42.1 °F | 3.67 in. |
| Annual | 43.4 °F | 63.7 °F | 47.72 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°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 |