| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 25°F | 42°F | 33°F | 4.1" |
| February | 19°F | 39°F | 29°F | 3.3" |
| March | 27°F | 51°F | 38°F | 7.5" |
| April | 39°F | 62°F | 50°F | 7.2" |
| May | 46°F | 73°F | 60°F | 3.6" |
| June | 60°F | 84°F | 72°F | 4.8" |
| July | 62°F | 86°F | 74°F | 7.7" |
| August | 63°F | 86°F | 74°F | 8.7" |
| September | 54°F | 81°F | 67°F | 0.4" |
| October | 47°F | 71°F | 58°F | 10.0" |
| November | 33°F | 57°F | 45°F | 4.7" |
| December | 23°F | 41°F | 33°F | 4.8" |
| Index | Dallastown | Pennsylvania | National |
| Air quality index | 41 | 45 | 42 |
| Pollution index | 12,532,500 | 4,584,805 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 299 |
| Days with moderate air quality | 66 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.180% |
| Benzene | 0.090% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.130% |
| Mercury | 0.270% |
| City | Population | Air Quality Index | National Avg. |
| Weigelstown, PA | 14,156 | 41 | 18.0% |
| Manchester, PA | 2,680 | 41 | 18.0% |
| Yorkana, PA | 207 | 41 | 18.0% |
| Glen Rock, PA | 2,332 | 41 | 18.0% |
| New Freedom, PA | 4,691 | 41 | 18.0% |
| Dallastown, PA | 3,889 | 41 | 18.0% |
| City | Population | Air Quality Index | National Avg. |
| Angels, CA | 3,889 | 39 | 22.0% |
| Menands, NY | 3,889 | 37 | 26.0% |
| Butte, AK | 3,888 | 31 | 38.0% |
| Canton, TX | 3,888 | 36 | 28.0% |
| Saint-Ambroise, QC | 3,888 | n/a | |
| Dallastown, PA | 3,889 | 41 | 18.0% |
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