| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 27°F | 48°F | 36°F | 4.1" |
| February | 28°F | 50°F | 38°F | 3.3" |
| March | 38°F | 63°F | 50°F | 5.5" |
| April | 47°F | 74°F | 60°F | 5.8" |
| May | 55°F | 80°F | 68°F | 4.9" |
| June | 65°F | 89°F | 77°F | 4.3" |
| July | 68°F | 91°F | 79°F | 5.2" |
| August | 66°F | 91°F | 78°F | 4.1" |
| September | 59°F | 85°F | 71°F | 3.9" |
| October | 47°F | 74°F | 59°F | 3.9" |
| November | 36°F | 62°F | 48°F | 4.2" |
| December | 29°F | 50°F | 39°F | 5.4" |
| Index | Massac | Kentucky | National |
| Air quality index | 44 | 45 | 42 |
| Pollution index | 1,566,340 | 1,369,131 | 2,726,193 |
| Measurement | Total |
| Days measured | 364 |
| Days with good air quality | 261 |
| Days with moderate air quality | 103 |
| 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 | 0.001% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Ledbetter, KY | 1,720 | 44 | 12.0% |
| Hendron, KY | 4,872 | 44 | 12.0% |
| Symsonia, KY | 529 | 44 | 12.0% |
| Kevil, KY | 768 | 44 | 12.0% |
| Bandana, KY | 302 | 44 | 12.0% |
| Massac, KY | 5,154 | 44 | 12.0% |
| City | Population | Air Quality Index | National Avg. |
| Silver Hill, MD | 5,155 | 47 | 6.0% |
| Sterling, AK | 5,150 | 31 | 38.0% |
| Floral City, FL | 5,158 | 30 | 40.0% |
| Johnstown, OH | 5,149 | 46 | 8.0% |
| Chisago City, MN | 5,159 | 46 | 8.0% |
| Massac, KY | 5,154 | 44 | 12.0% |
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