| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 35°F | 56°F | 45°F | 4.5" |
| February | 37°F | 59°F | 47°F | 3.0" |
| March | 45°F | 68°F | 56°F | 4.1" |
| April | 53°F | 77°F | 64°F | 4.1" |
| May | 61°F | 83°F | 71°F | 3.4" |
| June | 69°F | 90°F | 79°F | 3.7" |
| July | 71°F | 92°F | 80°F | 3.5" |
| August | 71°F | 91°F | 80°F | 5.7" |
| September | 66°F | 85°F | 74°F | 3.5" |
| October | 54°F | 76°F | 64°F | 3.8" |
| November | 43°F | 66°F | 54°F | 3.2" |
| December | 39°F | 59°F | 48°F | 5.1" |
| Index | Seneca | South Carolina | National |
| Air quality index | 41 | 37 | 42 |
| Pollution index | 770,308 | 3,620,438 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 308 |
| Days with moderate air quality | 56 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.004% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Centerville, SC | 6,816 | 31 | 38.0% |
| Martin, GA | 453 | 41 | 18.0% |
| Newry, SC | 98 | 41 | 18.0% |
| Utica, SC | 1,761 | 41 | 18.0% |
| Walhalla, SC | 4,377 | 41 | 18.0% |
| Seneca, SC | 8,424 | 41 | 18.0% |
| City | Population | Air Quality Index | National Avg. |
| Donaldsonville, LA | 8,424 | 45 | 10.0% |
| Perry Heights, OH | 8,423 | 46 | 8.0% |
| North Haledon, NJ | 8,425 | 51 | 2.0% |
| Dalhart, TX | 8,422 | 44 | 12.0% |
| Virginia, MN | 8,421 | 35 | 30.0% |
| Seneca, SC | 8,424 | 41 | 18.0% |
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