Westport, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.4 °C (low) to 17.6 °C (high). Annual precipitation averages 1212.1 Millimeters. 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 | -5.8 °C | 3.3 °C | 86.87 mm |
| February | -4.5 °C | 5.6 °C | 72.9 mm |
| March | 0.1 °C | 11.4 °C | 100.58 mm |
| April | 5.8 °C | 18.3 °C | 126.75 mm |
| May | 11.7 °C | 23.4 °C | 131.83 mm |
| June | 16.3 °C | 27.7 °C | 131.57 mm |
| July | 18.2 °C | 29.4 °C | 109.73 mm |
| August | 17.2 °C | 28.9 °C | 94.23 mm |
| September | 12.9 °C | 25.9 °C | 84.58 mm |
| October | 6.6 °C | 19.4 °C | 86.61 mm |
| November | 1 °C | 11.9 °C | 93.22 mm |
| December | -3.3 °C | 5.6 °C | 93.22 mm |
| Annual | 6.4 °C | 17.6 °C | 1212.09 mm |
| 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 : -20.6°C to -17.8°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 |