Grantsboro, North Carolina has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 11.6 °C (low) to 23 °C (high). Annual precipitation averages 1440.7 Millimeters. Grantsboro is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 1.6 °C | 13.1 °C | 98.81 mm |
| February | 2.5 °C | 14.7 °C | 85.34 mm |
| March | 5.6 °C | 18.2 °C | 92.46 mm |
| April | 10.5 °C | 23.3 °C | 84.58 mm |
| May | 15.3 °C | 26.9 °C | 110.74 mm |
| June | 19.8 °C | 30.5 °C | 136.91 mm |
| July | 21.8 °C | 32.1 °C | 172.21 mm |
| August | 21.2 °C | 31.1 °C | 187.96 mm |
| September | 18.6 °C | 28.6 °C | 179.83 mm |
| October | 12.3 °C | 23.9 °C | 101.85 mm |
| November | 6.5 °C | 18.7 °C | 95.25 mm |
| December | 3.2 °C | 14.8 °C | 94.74 mm |
| Annual | 11.6 °C | 23 °C | 1440.68 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |