Westphalia, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 38.5 °F (low) to 59 °F (high). Annual precipitation averages 34.2 Inches. Westphalia 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. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 11.4 °F | 29.1 °F | 0.85 in. |
| February | 15.7 °F | 33.9 °F | 1.05 in. |
| March | 25.9 °F | 47.4 °F | 1.93 in. |
| April | 37.3 °F | 60.7 °F | 3.57 in. |
| May | 49.5 °F | 71.2 °F | 4.83 in. |
| June | 59.8 °F | 80.5 °F | 4.96 in. |
| July | 63.7 °F | 83.7 °F | 3.76 in. |
| August | 61.1 °F | 81.8 °F | 4.25 in. |
| September | 51.9 °F | 75.7 °F | 3.59 in. |
| October | 40.5 °F | 63.7 °F | 2.64 in. |
| November | 27.4 °F | 46.9 °F | 1.44 in. |
| December | 17.2 °F | 33.9 °F | 1.29 in. |
| Annual | 38.5 °F | 59 °F | 34.16 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| 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 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |