Grand Blanc, Michigan has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.4 °C (low) to 13.9 °C (high). Annual precipitation averages 833.1 Millimeters. Grand Blanc 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 | -9.2 °C | -1.1 °C | 54.86 mm |
| February | -8.9 °C | 0.4 °C | 42.42 mm |
| March | -4.4 °C | 6.1 °C | 50.55 mm |
| April | 1.8 °C | 13.3 °C | 80.26 mm |
| May | 8.2 °C | 20 °C | 94.23 mm |
| June | 13.5 °C | 25.3 °C | 84.58 mm |
| July | 15.7 °C | 27.4 °C | 90.42 mm |
| August | 14.9 °C | 26.4 °C | 81.53 mm |
| September | 10.8 °C | 22.9 °C | 73.41 mm |
| October | 4.7 °C | 15.6 °C | 70.87 mm |
| November | -0.6 °C | 8.2 °C | 58.42 mm |
| December | -5.4 °C | 1.7 °C | 51.56 mm |
| Annual | 3.4 °C | 13.9 °C | 833.11 mm |
| 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 : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |