Grayson, Georgia has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 10.1 °C (low) to 21.8 °C (high). Annual precipitation averages 1344.4 Millimeters. Grayson is located in USDA Plant Hardiness Zone 8a. 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 | -0.2 °C | 10.9 °C | 123.95 mm |
| February | 1.4 °C | 13.1 °C | 121.16 mm |
| March | 4.7 °C | 17.6 °C | 127 mm |
| April | 9 °C | 22.2 °C | 105.66 mm |
| May | 14.1 °C | 26.2 °C | 97.79 mm |
| June | 18.5 °C | 29.7 °C | 119.63 mm |
| July | 20.4 °C | 31.3 °C | 122.94 mm |
| August | 20 °C | 30.8 °C | 111.76 mm |
| September | 16.6 °C | 27.8 °C | 98.04 mm |
| October | 10.4 °C | 22.8 °C | 90.17 mm |
| November | 4.3 °C | 17 °C | 106.17 mm |
| December | 1.5 °C | 12.4 °C | 120.14 mm |
| Annual | 10.1 °C | 21.8 °C | 1344.41 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 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |