Westfield, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 36.9 °F (low) to 59.5 °F (high). Annual precipitation averages 28.9 Inches. Westfield is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 9.2 °F | 28.8 °F | 0.62 in. |
| February | 13.3 °F | 34.0 °F | 0.75 in. |
| March | 24.7 °F | 46.7 °F | 1.64 in. |
| April | 35.8 °F | 60.8 °F | 3.1 in. |
| May | 48.2 °F | 71.9 °F | 4.07 in. |
| June | 59.5 °F | 82.2 °F | 4.51 in. |
| July | 63.0 °F | 85.5 °F | 3.3 in. |
| August | 60.5 °F | 83.4 °F | 3.29 in. |
| September | 51.0 °F | 76.9 °F | 2.94 in. |
| October | 38.0 °F | 63.6 °F | 2.47 in. |
| November | 24.9 °F | 46.9 °F | 1.31 in. |
| December | 14.4 °F | 33.1 °F | 0.92 in. |
| Annual | 36.9 °F | 59.5 °F | 28.92 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |