Grand River, Ohio has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 6.2 °C (low) to 14.5 °C (high). Annual precipitation averages 1054.4 Millimeters. Grand River is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.9 °C | 1.4 °C | 79.5 mm |
| February | -5.7 °C | 2.2 °C | 55.63 mm |
| March | -2 °C | 6.2 °C | 73.41 mm |
| April | 4.1 °C | 13.4 °C | 92.2 mm |
| May | 10.3 °C | 19.4 °C | 89.15 mm |
| June | 15.7 °C | 24.4 °C | 91.69 mm |
| July | 18.2 °C | 26.6 °C | 107.95 mm |
| August | 17.6 °C | 26.1 °C | 92.71 mm |
| September | 13.8 °C | 22.9 °C | 102.11 mm |
| October | 8 °C | 16.6 °C | 103.63 mm |
| November | 2.6 °C | 10.1 °C | 86.61 mm |
| December | -2.2 °C | 4.2 °C | 79.76 mm |
| Annual | 6.2 °C | 14.5 °C | 1054.35 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |