Westwood, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.3 °C (low) to 16.3 °C (high). Annual precipitation averages 959.4 Millimeters. 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 | -9.2 °C | -0.1 °C | 36.07 mm |
| February | -7.1 °C | 2.6 °C | 43.18 mm |
| March | -1.4 °C | 9.6 °C | 61.47 mm |
| April | 4.7 °C | 17.1 °C | 93.73 mm |
| May | 11.2 °C | 22.8 °C | 130.3 mm |
| June | 16.7 °C | 27.9 °C | 126.24 mm |
| July | 18.6 °C | 29.8 °C | 105.66 mm |
| August | 17.4 °C | 29 °C | 98.3 mm |
| September | 12.5 °C | 25.4 °C | 91.95 mm |
| October | 6.1 °C | 18.3 °C | 73.15 mm |
| November | -0.2 °C | 9.8 °C | 55.63 mm |
| December | -5.9 °C | 2.8 °C | 43.69 mm |
| Annual | 5.3 °C | 16.3 °C | 959.37 mm |
| 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 : -26.1°C to -23.3°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 |