| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 32°F | 54°F | 42°F | 2.6" |
| February | 34°F | 57°F | 45°F | 2.2" |
| March | 42°F | 66°F | 53°F | 2.7" |
| April | 50°F | 75°F | 62°F | 2.7" |
| May | 58°F | 81°F | 69°F | 2.9" |
| June | 66°F | 89°F | 77°F | 3.3" |
| July | 69°F | 91°F | 79°F | 3.1" |
| August | 69°F | 90°F | 78°F | 4.1" |
| September | 63°F | 84°F | 72°F | 3.0" |
| October | 50°F | 74°F | 61°F | 2.6" |
| November | 40°F | 64°F | 51°F | 2.9" |
| December | 37°F | 58°F | 46°F | 3.4" |
| Index | Jefferson | South Carolina | National |
| Air quality index | 49 | 37 | 42 |
| Pollution index | 1,817,360 | 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 | 0.010% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.020% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| McBee, SC | 977 | 40 | 20.0% |
| Ruby, SC | 304 | 40 | 20.0% |
| Kershaw, SC | 1,765 | 43 | 14.0% |
| Mount Croghan, SC | 142 | 49 | 2.0% |
| Pageland, SC | 2,556 | 49 | 2.0% |
| Jefferson, SC | 1,118 | 49 | 2.0% |
| City | Population | Air Quality Index | National Avg. |
| Wilson, AR | 1,118 | 45 | 10.0% |
| Andalusia, IL | 1,118 | 46 | 8.0% |
| Williamsburg, PA | 1,118 | 41 | 18.0% |
| Kitchenuhmaykoosib Aaki 84 (Big Trout Lake), ON | 1,118 | n/a | |
| Spiritwood No. 496, SK | 1,118 | n/a | |
| Jefferson, SC | 1,118 | 49 | 2.0% |
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