Howell, Michigan has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 38.2 °F (low) to 57.8 °F (high). Annual precipitation averages 33.3 Inches. Howell 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 | 15.6 °F | 30.5 °F | 2.18 in. |
| February | 16.3 °F | 33.4 °F | 1.66 in. |
| March | 24.4 °F | 43.7 °F | 2.01 in. |
| April | 35.7 °F | 57.0 °F | 3.16 in. |
| May | 46.9 °F | 69.0 °F | 3.65 in. |
| June | 56.4 °F | 78.4 °F | 3.69 in. |
| July | 59.8 °F | 82.4 °F | 3.18 in. |
| August | 58.7 °F | 80.6 °F | 3.38 in. |
| September | 51.3 °F | 74.2 °F | 3.17 in. |
| October | 40.3 °F | 61.1 °F | 2.77 in. |
| November | 30.7 °F | 47.3 °F | 2.43 in. |
| December | 22.1 °F | 35.6 °F | 2.02 in. |
| Annual | 38.2 °F | 57.8 °F | 33.3 in. |
| 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 : -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 |