| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 18°F | 36°F | 27°F | 3.5" |
| February | 18°F | 37°F | 27°F | 3.0" |
| March | 27°F | 49°F | 37°F | 3.6" |
| April | 37°F | 64°F | 50°F | 3.6" |
| May | 47°F | 73°F | 60°F | 4.1" |
| June | 56°F | 81°F | 68°F | 4.4" |
| July | 59°F | 84°F | 72°F | 4.6" |
| August | 58°F | 83°F | 70°F | 3.9" |
| September | 52°F | 77°F | 64°F | 3.6" |
| October | 42°F | 64°F | 52°F | 4.2" |
| November | 32°F | 53°F | 42°F | 3.1" |
| December | 24°F | 41°F | 32°F | 3.8" |
| Index | Clark | Pennsylvania | National |
| Air quality index | 42 | 45 | 42 |
| Pollution index | 601,986 | 4,584,805 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 276 |
| Days with moderate air quality | 89 |
| 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 | 0.010% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| New Wilmington, PA | 2,196 | 31 | 38.0% |
| Jackson Center, PA | 173 | 31 | 38.0% |
| Volant, PA | 100 | 31 | 38.0% |
| Stoneboro, PA | 752 | 31 | 38.0% |
| Lake Latonka, PA | 756 | 31 | 38.0% |
| Clark, PA | 562 | 42 | 16.0% |
| City | Population | Air Quality Index | National Avg. |
| Noorvik, AK | 562 | 38 | 24.0% |
| Natural Steps, AR | 562 | 45 | 10.0% |
| Springfield, LA | 562 | 30 | 40.0% |
| Fisk, MO | 562 | 26 | 48.0% |
| Exeter, NE | 562 | 31 | 38.0% |
| Clark, PA | 562 | 42 | 16.0% |
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