| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 34°F | 57°F | 44°F | 4.7" |
| February | 32°F | 56°F | 43°F | 4.9" |
| March | 40°F | 67°F | 53°F | 9.2" |
| April | 46°F | 73°F | 59°F | 5.1" |
| May | 54°F | 80°F | 67°F | 3.1" |
| June | 65°F | 87°F | 75°F | 7.7" |
| July | 69°F | 90°F | 78°F | 6.0" |
| August | 71°F | 93°F | 81°F | 3.6" |
| September | 63°F | 88°F | 75°F | 1.5" |
| October | 54°F | 77°F | 64°F | 3.9" |
| November | 39°F | 66°F | 52°F | 4.6" |
| December | 34°F | 58°F | 44°F | 7.2" |
| Index | Fort Mill | South Carolina | National |
| Air quality index | 49 | 37 | 42 |
| Pollution index | 5,729,570 | 3,620,438 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 200 |
| Days with moderate air quality | 147 |
| Days w/ poor A.Q. for sensitive groups | 18 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 4.280% |
| Benzene | 0.050% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.130% |
| Mercury | 0.040% |
| City | Population | Air Quality Index | National Avg. |
| JAARS, NC | 1,120 | 49 | 2.0% |
| Lake Wylie, SC | 14,454 | 49 | 2.0% |
| Rock Hill, SC | 76,923 | 49 | 2.0% |
| Mineral Springs, NC | 3,124 | 49 | 2.0% |
| Wesley Chapel, NC | 9,595 | 49 | 2.0% |
| Fort Mill, SC | 20,703 | 49 | 2.0% |
| City | Population | Air Quality Index | National Avg. |
| Tukwila, WA | 20,710 | 45 | 10.0% |
| Charleston, IL | 20,693 | 40 | 20.0% |
| Rio Rico, AZ | 20,721 | 31 | 38.0% |
| Cobourg, ON | 20,684 | n/a | |
| Shelby, NC | 20,722 | 36 | 28.0% |
| Fort Mill, SC | 20,703 | 49 | 2.0% |