| 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 | Manchester | Maryland | National |
| Air quality index | 42 | 43 | 42 |
| Pollution index | 12,532,500 | 5,342,367 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 288 |
| Days with moderate air quality | 77 |
| 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. |
| Jefferson, PA | 606 | 41 | 18.0% |
| Winterstown, PA | 521 | 41 | 18.0% |
| Glen Rock, PA | 2,332 | 41 | 18.0% |
| Loganville, PA | 1,311 | 41 | 18.0% |
| New Freedom, PA | 4,691 | 41 | 18.0% |
| Manchester, MD | 4,752 | 42 | 16.0% |
| City | Population | Air Quality Index | National Avg. |
| Seat Pleasant, MD | 4,753 | 47 | 6.0% |
| Crystal Springs, MS | 4,753 | 44 | 12.0% |
| Columbia, KY | 4,748 | 40 | 20.0% |
| East Harwich, MA | 4,756 | 36 | 28.0% |
| Guerneville, CA | 4,747 | 34 | 32.0% |
| Manchester, MD | 4,752 | 42 | 16.0% |
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