| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 38°F | 61°F | 49°F | 4.4" |
| February | 37°F | 60°F | 48°F | 6.9" |
| March | 43°F | 70°F | 56°F | 7.0" |
| April | 49°F | 76°F | 62°F | 7.0" |
| May | 56°F | 83°F | 69°F | 4.0" |
| June | 68°F | 88°F | 77°F | 7.7" |
| July | 71°F | 91°F | 80°F | 10.1" |
| August | 73°F | 93°F | 82°F | 7.0" |
| September | 67°F | 89°F | 77°F | 3.3" |
| October | 58°F | 80°F | 68°F | 5.5" |
| November | 43°F | 71°F | 56°F | 3.5" |
| December | 40°F | 63°F | 50°F | 7.2" |
| Index | Harleyville | South Carolina | National |
| Air quality index | 29 | 37 | 42 |
| Pollution index | 783,589 | 3,620,438 | 2,726,193 |
| Measurement | Total |
| Days measured | 7 |
| Days with good air quality | 7 |
| Days with moderate air quality | 0 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.003% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Eutawville, SC | 515 | 29 | 42.0% |
| Reevesville, SC | 233 | 29 | 42.0% |
| Holly Hill, SC | 1,469 | 29 | 42.0% |
| St. George, SC | 2,209 | 29 | 42.0% |
| Ridgeville, SC | 1,849 | 29 | 42.0% |
| Harleyville, SC | 658 | 29 | 42.0% |
| City | Population | Air Quality Index | National Avg. |
| Ona, FL | 658 | 36 | 28.0% |
| Melba, ID | 658 | 36 | 28.0% |
| Marengo, IN | 658 | 6 | 88.0% |
| Russell, MA | 658 | 40 | 20.0% |
| Marshall, NC | 658 | 44 | 12.0% |
| Harleyville, SC | 658 | 29 | 42.0% |
Here are the best places to live in South Carolina
Check out the 10 most dangerous cities in South Carolina
Check out the 10 safest cities in South Carolina
Most Dangerous Cities In The US