Harleyville, South Carolina has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 54 °F (low) to 76 °F (high). Annual precipitation averages 50.9 Inches. 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 | 36.1 °F | 58.8 °F | 3.65 in. |
| February | 38.5 °F | 62.2 °F | 3.76 in. |
| March | 44.5 °F | 69.0 °F | 3.75 in. |
| April | 52.2 °F | 76.7 °F | 3.54 in. |
| May | 60.9 °F | 83.2 °F | 3.75 in. |
| June | 68.6 °F | 88.8 °F | 5.74 in. |
| July | 71.8 °F | 91.7 °F | 5.79 in. |
| August | 71.1 °F | 89.9 °F | 5.46 in. |
| September | 66.2 °F | 85.2 °F | 5.08 in. |
| October | 55.0 °F | 77.2 °F | 3.91 in. |
| November | 44.0 °F | 68.1 °F | 2.71 in. |
| December | 38.7 °F | 61.1 °F | 3.8 in. |
| Annual | 54 °F | 76 °F | 50.94 in. |
| 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 : 15°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |