| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 20°F | 39°F | 29°F | 3.4" |
| February | 22°F | 42°F | 31°F | 1.4" |
| March | 32°F | 56°F | 42°F | 2.6" |
| April | 41°F | 69°F | 54°F | 3.1" |
| May | 53°F | 77°F | 64°F | 3.2" |
| June | 60°F | 84°F | 71°F | 4.4" |
| July | 64°F | 86°F | 74°F | 5.4" |
| August | 61°F | 86°F | 72°F | 5.0" |
| September | 54°F | 79°F | 65°F | 2.7" |
| October | 43°F | 68°F | 54°F | 2.4" |
| November | 32°F | 56°F | 42°F | 4.6" |
| December | 27°F | 44°F | 35°F | 4.0" |
| Index | Mason | West Virginia | National |
| Air quality index | 25 | 126 | 42 |
| Pollution index | 874,439 | 1,996,538 | 2,726,193 |
| Measurement | Total |
| Days measured | 120 |
| Days with good air quality | 116 |
| Days with moderate air quality | 4 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.002% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.010% |
| Mercury | 0.010% |
| City | Population | Air Quality Index | National Avg. |
| Cheshire, OH | 160 | 25 | 50.0% |
| Syracuse, OH | 766 | 25 | 50.0% |
| Middleport, OH | 2,417 | 25 | 50.0% |
| Hartford City, WV | 576 | 25 | 50.0% |
| Tuppers Plains, OH | 382 | 25 | 50.0% |
| Mason, WV | 738 | 25 | 50.0% |
| City | Population | Air Quality Index | National Avg. |
| Addison, AL | 738 | 41 | 18.0% |
| Elaine, AR | 738 | 43 | 14.0% |
| Bancroft, IA | 738 | 15 | 70.0% |
| Artemus, KY | 738 | 39 | 22.0% |
| Pray, MT | 738 | 25 | 50.0% |
| Mason, WV | 738 | 25 | 50.0% |