| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 25°F | 47°F | 35°F | 3.4" |
| February | 26°F | 48°F | 36°F | 2.8" |
| March | 35°F | 60°F | 46°F | 4.1" |
| April | 44°F | 73°F | 58°F | 3.9" |
| May | 52°F | 78°F | 64°F | 4.6" |
| June | 61°F | 86°F | 72°F | 4.9" |
| July | 64°F | 88°F | 75°F | 6.2" |
| August | 63°F | 87°F | 74°F | 3.8" |
| September | 57°F | 82°F | 68°F | 3.2" |
| October | 45°F | 71°F | 57°F | 3.7" |
| November | 35°F | 61°F | 46°F | 2.6" |
| December | 30°F | 50°F | 39°F | 4.4" |
| Index | Clay | West Virginia | National |
| Air quality index | 40 | 126 | 42 |
| Pollution index | 231,791 | 1,996,538 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 314 |
| Days with moderate air quality | 51 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.003% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Clendenin, WV | 1,405 | 40 | 20.0% |
| Dixie, WV | 214 | 40 | 20.0% |
| Summersville, WV | 3,443 | 295 | 490.0% |
| Clay, WV | 737 | 40 | 20.0% |
| City | Population | Air Quality Index | National Avg. |
| Stillmore, GA | 737 | 47 | 6.0% |
| Hanover, IL | 737 | 42 | 16.0% |
| Jackson Heights, NC | 737 | 42 | 16.0% |
| Glen Ullin, ND | 737 | 33 | 34.0% |
| Chazy, NY | 737 | 37 | 26.0% |
| Clay, WV | 737 | 40 | 20.0% |