| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 24°F | 42°F | 32°F | 3.2" |
| February | 25°F | 43°F | 33°F | 2.4" |
| March | 33°F | 55°F | 43°F | 3.9" |
| April | 43°F | 68°F | 55°F | 4.1" |
| May | 52°F | 75°F | 63°F | 4.3" |
| June | 60°F | 82°F | 71°F | 4.8" |
| July | 64°F | 85°F | 74°F | 6.0" |
| August | 63°F | 84°F | 73°F | 4.0" |
| September | 57°F | 79°F | 67°F | 3.2" |
| October | 46°F | 67°F | 56°F | 3.9" |
| November | 36°F | 57°F | 46°F | 2.7" |
| December | 29°F | 46°F | 37°F | 4.1" |
| Index | Markleysburg | Pennsylvania | National |
| Air quality index | 36 | 45 | 42 |
| Pollution index | 6,478,770 | 4,584,805 | 2,726,193 |
| Measurement | Total |
| Days measured | 359 |
| Days with good air quality | 340 |
| Days with moderate air quality | 19 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.030% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.020% |
| Mercury | 0.210% |
| City | Population | Air Quality Index | National Avg. |
| Friendsville, MD | 430 | 36 | 28.0% |
| Confluence, PA | 597 | 36 | 28.0% |
| Farmington, PA | 983 | 36 | 28.0% |
| Lemont Furnace, PA | 897 | 36 | 28.0% |
| New Centerville, PA | 112 | 36 | 28.0% |
| Markleysburg, PA | 303 | 36 | 28.0% |
| City | Population | Air Quality Index | National Avg. |
| Twain, CA | 303 | 46 | 8.0% |
| Surrency, GA | 303 | 26 | 48.0% |
| Bagley, IA | 303 | 37 | 26.0% |
| Bush, IL | 303 | 43 | 14.0% |
| Opdyke, IL | 303 | 43 | 14.0% |
| Markleysburg, PA | 303 | 36 | 28.0% |
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