Custer, Michigan has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 36.4 °F (low) to 55.6 °F (high). Annual precipitation averages 35.5 Inches. Custer is located in USDA Plant Hardiness Zone 6a. 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 | 15.8 °F | 29.1 °F | 2.61 in. |
| February | 16.1 °F | 31.8 °F | 1.89 in. |
| March | 22.0 °F | 41.3 °F | 2.23 in. |
| April | 32.8 °F | 54.4 °F | 3.32 in. |
| May | 43.7 °F | 67.2 °F | 3.45 in. |
| June | 53.3 °F | 76.3 °F | 3.38 in. |
| July | 57.7 °F | 79.3 °F | 2.8 in. |
| August | 55.9 °F | 78.2 °F | 3.23 in. |
| September | 48.6 °F | 71.5 °F | 2.91 in. |
| October | 38.4 °F | 58.8 °F | 3.88 in. |
| November | 30.1 °F | 44.7 °F | 3.17 in. |
| December | 22.2 °F | 34.0 °F | 2.63 in. |
| Annual | 36.4 °F | 55.6 °F | 35.5 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 6a : -10°F to -5°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 |