Westfield, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.8 °C (low) to 16.4 °C (high). Annual precipitation averages 1093 Millimeters. Westfield 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.1 °C | 1.5 °C | 72.39 mm |
| February | -5.7 °C | 3.7 °C | 60.71 mm |
| March | -0.8 °C | 9.7 °C | 83.06 mm |
| April | 5.1 °C | 16.8 °C | 110.49 mm |
| May | 11.3 °C | 22.5 °C | 119.13 mm |
| June | 16.3 °C | 27.1 °C | 131.06 mm |
| July | 17.9 °C | 28.8 °C | 108.97 mm |
| August | 16.9 °C | 28.1 °C | 80.77 mm |
| September | 12.7 °C | 25.1 °C | 85.34 mm |
| October | 6.4 °C | 18.4 °C | 80.77 mm |
| November | 0.7 °C | 10.5 °C | 85.6 mm |
| December | -4.2 °C | 4 °C | 74.68 mm |
| Annual | 5.8 °C | 16.4 °C | 1092.97 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 |