Flat Rock, Michigan has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41.2 °F (low) to 59 °F (high). Annual precipitation averages 35.5 Inches. Flat Rock is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 18.7 °F | 32.5 °F | 2.42 in. |
| February | 19.8 °F | 35.1 °F | 2.1 in. |
| March | 27.6 °F | 44.9 °F | 2.55 in. |
| April | 38.2 °F | 58.0 °F | 3.2 in. |
| May | 49.5 °F | 69.7 °F | 3.81 in. |
| June | 59.4 °F | 79.3 °F | 3.52 in. |
| July | 63.4 °F | 83.2 °F | 3.35 in. |
| August | 61.9 °F | 81.4 °F | 3.42 in. |
| September | 54.6 °F | 75.1 °F | 3.25 in. |
| October | 43.0 °F | 62.3 °F | 2.8 in. |
| November | 33.2 °F | 48.8 °F | 2.7 in. |
| December | 25.1 °F | 37.6 °F | 2.4 in. |
| Annual | 41.2 °F | 59 °F | 35.52 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |