| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 24°F | 39°F | 31°F | 2.9" |
| February | 26°F | 42°F | 33°F | 2.8" |
| March | 34°F | 53°F | 43°F | 4.1" |
| April | 44°F | 65°F | 54°F | 4.9" |
| May | 53°F | 73°F | 63°F | 4.8" |
| June | 62°F | 82°F | 71°F | 5.4" |
| July | 66°F | 86°F | 76°F | 4.0" |
| August | 64°F | 84°F | 73°F | 4.2" |
| September | 58°F | 77°F | 67°F | 5.2" |
| October | 48°F | 67°F | 57°F | 5.8" |
| November | 38°F | 55°F | 46°F | 3.1" |
| December | 31°F | 45°F | 38°F | 4.6" |
| Index | Orrstown | Pennsylvania | National |
| Air quality index | 36 | 45 | 42 |
| Pollution index | 1,656,460 | 4,584,805 | 2,726,193 |
| Measurement | Total |
| Days measured | 341 |
| Days with good air quality | 324 |
| Days with moderate air quality | 17 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.005% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.004% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Fayetteville, PA | 2,855 | 36 | 28.0% |
| Orbisonia, PA | 449 | 36 | 28.0% |
| Newville, PA | 1,231 | 36 | 28.0% |
| Marion, PA | 1,551 | 36 | 28.0% |
| Guilford, PA | 3,571 | 36 | 28.0% |
| Orrstown, PA | 342 | 36 | 28.0% |
| City | Population | Air Quality Index | National Avg. |
| Montrose, GA | 342 | 38 | 24.0% |
| Oliver, GA | 342 | 39 | 22.0% |
| Persia, IA | 342 | 40 | 20.0% |
| Alto Pass, IL | 342 | 44 | 12.0% |
| Williamsburg, KS | 342 | 22 | 56.0% |
| Orrstown, PA | 342 | 36 | 28.0% |
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