Harbor Beach, Michigan has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 39 °F (low) to 53.5 °F (high). Annual precipitation averages 33.7 Inches. Harbor Beach is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 16.9 °F | 29.2 °F | 2.33 in. |
| February | 16.7 °F | 30.8 °F | 1.98 in. |
| March | 24.6 °F | 38.8 °F | 1.94 in. |
| April | 34.6 °F | 49.3 °F | 3.22 in. |
| May | 45.1 °F | 61.1 °F | 3.35 in. |
| June | 55.3 °F | 71.2 °F | 3.36 in. |
| July | 61.1 °F | 76.9 °F | 2.97 in. |
| August | 60.2 °F | 76.2 °F | 3.42 in. |
| September | 53.3 °F | 70.2 °F | 3.28 in. |
| October | 43.1 °F | 58.0 °F | 2.97 in. |
| November | 33.1 °F | 45.8 °F | 2.6 in. |
| December | 24.2 °F | 35.0 °F | 2.3 in. |
| Annual | 39 °F | 53.5 °F | 33.72 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| 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 |