Westwood, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41.5 °F (low) to 61.3 °F (high). Annual precipitation averages 37.8 Inches. Westwood is located in USDA Plant Hardiness Zone 5b. 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 | 15.4 °F | 31.9 °F | 1.42 in. |
| February | 19.2 °F | 36.6 °F | 1.7 in. |
| March | 29.5 °F | 49.3 °F | 2.42 in. |
| April | 40.5 °F | 62.7 °F | 3.69 in. |
| May | 52.2 °F | 73.0 °F | 5.13 in. |
| June | 62.0 °F | 82.2 °F | 4.97 in. |
| July | 65.5 °F | 85.7 °F | 4.16 in. |
| August | 63.3 °F | 84.2 °F | 3.87 in. |
| September | 54.5 °F | 77.8 °F | 3.62 in. |
| October | 43.0 °F | 64.9 °F | 2.88 in. |
| November | 31.6 °F | 49.7 °F | 2.19 in. |
| December | 21.3 °F | 37.1 °F | 1.72 in. |
| Annual | 41.5 °F | 61.3 °F | 37.77 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |