| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 35°F | 58°F | 46°F | 2.4" |
| February | 36°F | 61°F | 48°F | 3.7" |
| March | 43°F | 69°F | 55°F | 3.2" |
| April | 52°F | 78°F | 64°F | 3.5" |
| May | 60°F | 84°F | 71°F | 4.7" |
| June | 69°F | 90°F | 79°F | 4.8" |
| July | 72°F | 92°F | 81°F | 6.4" |
| August | 71°F | 91°F | 80°F | 4.5" |
| September | 66°F | 86°F | 75°F | 5.1" |
| October | 54°F | 77°F | 64°F | 4.2" |
| November | 42°F | 68°F | 54°F | 2.8" |
| December | 39°F | 62°F | 50°F | 4.0" |
| Index | Marion | South Carolina | National |
| Air quality index | 40 | 37 | 42 |
| Pollution index | 940,521 | 3,620,438 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 288 |
| Days with moderate air quality | 77 |
| 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 | 0.002% |
| Lead | 0.003% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Nichols, SC | 228 | 30 | 40.0% |
| Lake View, SC | 714 | 30 | 40.0% |
| Aynor, SC | 785 | 40 | 20.0% |
| Pamplico, SC | 1,222 | 40 | 20.0% |
| Mullins, SC | 4,276 | 40 | 20.0% |
| Marion, SC | 6,598 | 40 | 20.0% |
| City | Population | Air Quality Index | National Avg. |
| Torrington, WY | 6,597 | 19 | 62.0% |
| Desert Palms, CA | 6,599 | 89 | 78.0% |
| Bedford, VA | 6,599 | 26 | 48.0% |
| Atlantic, IA | 6,600 | 40 | 20.0% |
| Anadarko, OK | 6,600 | 43 | 14.0% |
| Marion, SC | 6,598 | 40 | 20.0% |
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