| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 23°F | 42°F | 32°F | 3.2" |
| February | 24°F | 43°F | 33°F | 2.5" |
| March | 34°F | 56°F | 44°F | 3.9" |
| April | 43°F | 68°F | 55°F | 4.1" |
| May | 51°F | 75°F | 63°F | 4.1" |
| June | 59°F | 82°F | 70°F | 5.3" |
| July | 63°F | 84°F | 73°F | 6.0" |
| August | 61°F | 84°F | 72°F | 3.6" |
| September | 55°F | 78°F | 66°F | 3.5" |
| October | 44°F | 67°F | 55°F | 3.6" |
| November | 34°F | 56°F | 44°F | 2.3" |
| December | 29°F | 47°F | 37°F | 4.2" |
| Index | Smithfield | West Virginia | National |
| Air quality index | 31 | 126 | 42 |
| Pollution index | 505,265 | 1,996,538 | 2,726,193 |
| Measurement | Total |
| Days measured | 111 |
| Days with good air quality | 101 |
| Days with moderate air quality | 10 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.003% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.002% |
| Mercury | 0.010% |
| City | Population | Air Quality Index | National Avg. |
| Enterprise, WV | 1,115 | 31 | 38.0% |
| Wolf Summit, WV | 123 | 31 | 38.0% |
| Spelter, WV | 233 | 31 | 38.0% |
| Mannington, WV | 1,608 | 31 | 38.0% |
| Shinnston, WV | 2,288 | 31 | 38.0% |
| Smithfield, WV | 169 | 31 | 38.0% |
| City | Population | Air Quality Index | National Avg. |
| Vernon, AZ | 169 | 44 | 12.0% |
| Farmington, CA | 169 | 45 | 10.0% |
| Sisquoc, CA | 169 | 46 | 8.0% |
| Castalia, IA | 169 | 35 | 30.0% |
| Admire, KS | 169 | 22 | 56.0% |
| Smithfield, WV | 169 | 31 | 38.0% |
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