| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 22°F | 42°F | 32°F | 3.4" |
| February | 23°F | 44°F | 33°F | 3.1" |
| March | 33°F | 57°F | 44°F | 4.6" |
| April | 43°F | 69°F | 56°F | 5.0" |
| May | 52°F | 77°F | 64°F | 4.0" |
| June | 61°F | 85°F | 73°F | 5.2" |
| July | 65°F | 87°F | 76°F | 4.0" |
| August | 64°F | 88°F | 76°F | 3.0" |
| September | 57°F | 81°F | 69°F | 4.1" |
| October | 45°F | 69°F | 57°F | 4.1" |
| November | 34°F | 57°F | 45°F | 3.5" |
| December | 27°F | 45°F | 36°F | 4.5" |
| Index | Williamstown | Kentucky | National |
| Air quality index | 54 | 45 | 42 |
| Pollution index | 746,363 | 1,369,131 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 139 |
| Days with moderate air quality | 206 |
| Days w/ poor A.Q. for sensitive groups | 20 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.060% |
| Lead | 0.020% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Corinth, KY | 273 | 42 | 16.0% |
| Owenton, KY | 1,701 | 42 | 16.0% |
| Berry, KY | 181 | 42 | 16.0% |
| Butler, KY | 720 | 54 | 8.0% |
| Glencoe, KY | 333 | 54 | 8.0% |
| Williamstown, KY | 3,914 | 54 | 8.0% |
| City | Population | Air Quality Index | National Avg. |
| Shannon Hills, AR | 3,914 | 45 | 10.0% |
| Florence, CO | 3,913 | 16 | 68.0% |
| Highland Acres, DE | 3,913 | 42 | 16.0% |
| Red Oaks Mill, NY | 3,913 | 36 | 28.0% |
| Parkesburg, PA | 3,913 | 45 | 10.0% |
| Williamstown, KY | 3,914 | 54 | 8.0% |
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