Westphalia, Michigan has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.5 °C (low) to 14.1 °C (high). Annual precipitation averages 898.7 Millimeters. Westphalia is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.1 °C | -1.3 °C | 57.91 mm |
| February | -8.4 °C | 0.6 °C | 52.32 mm |
| March | -3.9 °C | 6.4 °C | 55.63 mm |
| April | 1.7 °C | 13.8 °C | 88.39 mm |
| May | 8.4 °C | 20.6 °C | 99.57 mm |
| June | 13.7 °C | 25.7 °C | 91.69 mm |
| July | 15.7 °C | 27.8 °C | 82.8 mm |
| August | 14.8 °C | 26.7 °C | 89.41 mm |
| September | 10.3 °C | 23 °C | 75.44 mm |
| October | 4.4 °C | 15.8 °C | 83.82 mm |
| November | -0.6 °C | 8.2 °C | 67.82 mm |
| December | -5.4 °C | 1.7 °C | 53.85 mm |
| Annual | 3.5 °C | 14.1 °C | 898.65 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |