Westfield, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 5.7 °C (low) to 14.2 °C (high). Annual precipitation averages 1068.1 Millimeters. Westfield is located in USDA Plant Hardiness Zone 6b. 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 | -6.3 °C | 1.1 °C | 75.18 mm |
| February | -6.4 °C | 1.7 °C | 57.91 mm |
| March | -2.8 °C | 5.9 °C | 71.37 mm |
| April | 3.1 °C | 13.1 °C | 86.61 mm |
| May | 9.4 °C | 19.3 °C | 87.63 mm |
| June | 15.1 °C | 24.3 °C | 89.66 mm |
| July | 17.7 °C | 26.4 °C | 104.65 mm |
| August | 17.1 °C | 25.9 °C | 83.82 mm |
| September | 13.4 °C | 22.6 °C | 110.74 mm |
| October | 7.6 °C | 16.1 °C | 117.35 mm |
| November | 2.2 °C | 9.7 °C | 96.01 mm |
| December | -2.3 °C | 3.9 °C | 87.12 mm |
| Annual | 5.7 °C | 14.2 °C | 1068.05 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 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |