Pentwater, Michigan has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 39.4 °F (low) to 54.5 °F (high). Annual precipitation averages 35.7 Inches. Pentwater is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 18.9 °F | 29.8 °F | 2.42 in. |
| February | 19.3 °F | 31.7 °F | 1.81 in. |
| March | 24.9 °F | 39.9 °F | 2.11 in. |
| April | 35.0 °F | 52.6 °F | 3.37 in. |
| May | 45.0 °F | 64.3 °F | 3.65 in. |
| June | 54.7 °F | 73.7 °F | 3.41 in. |
| July | 60.5 °F | 77.4 °F | 3.24 in. |
| August | 60.3 °F | 76.5 °F | 3.37 in. |
| September | 53.4 °F | 70.3 °F | 3.09 in. |
| October | 42.3 °F | 57.8 °F | 3.83 in. |
| November | 33.2 °F | 45.2 °F | 3.01 in. |
| December | 24.7 °F | 34.8 °F | 2.42 in. |
| Annual | 39.4 °F | 54.5 °F | 35.73 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |