| 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 | Williams | South Carolina | National |
| Air quality index | 29 | 37 | 42 |
| Pollution index | 6,343,880 | 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 | 0.050% |
| Benzene | 0.050% |
| Carbon Tetrachloride | 0.090% |
| Lead | 0.010% |
| Mercury | 0.100% |
| City | Population | Air Quality Index | National Avg. |
| Islandton, SC | 49 | 29 | 42.0% |
| Ehrhardt, SC | 444 | 29 | 42.0% |
| Varnville, SC | 1,832 | 29 | 42.0% |
| Lodge, SC | 142 | 29 | 42.0% |
| Walterboro, SC | 5,417 | 29 | 42.0% |
| Williams, SC | 194 | 29 | 42.0% |
| City | Population | Air Quality Index | National Avg. |
| Laurel, IA | 194 | 37 | 26.0% |
| Gilson, IL | 194 | 41 | 18.0% |
| Bison, KS | 194 | 15 | 70.0% |
| Maple Grove, MI | 194 | 36 | 28.0% |
| Bolckow, MO | 194 | 43 | 14.0% |
| Williams, SC | 194 | 29 | 42.0% |
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