Harleyville, South Carolina has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 12.2 °C (low) to 24.5 °C (high). Annual precipitation averages 1293.9 Millimeters. Harleyville 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 | 2.3 °C | 14.9 °C | 92.71 mm |
| February | 3.6 °C | 16.8 °C | 95.5 mm |
| March | 6.9 °C | 20.6 °C | 95.25 mm |
| April | 11.2 °C | 24.8 °C | 89.92 mm |
| May | 16.1 °C | 28.4 °C | 95.25 mm |
| June | 20.3 °C | 31.6 °C | 145.8 mm |
| July | 22.1 °C | 33.2 °C | 147.07 mm |
| August | 21.7 °C | 32.2 °C | 138.68 mm |
| September | 19 °C | 29.6 °C | 129.03 mm |
| October | 12.8 °C | 25.1 °C | 99.31 mm |
| November | 6.7 °C | 20.1 °C | 68.83 mm |
| December | 3.7 °C | 16.2 °C | 96.52 mm |
| Annual | 12.2 °C | 24.5 °C | 1293.87 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 30-40 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |