| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 21°F | 36°F | 28°F | 4.1" |
| February | 20°F | 37°F | 28°F | 3.0" |
| March | 30°F | 49°F | 39°F | 5.9" |
| April | 40°F | 63°F | 51°F | 4.9" |
| May | 50°F | 72°F | 60°F | 4.9" |
| June | 58°F | 79°F | 68°F | 7.2" |
| July | 62°F | 82°F | 71°F | 7.6" |
| August | 60°F | 80°F | 69°F | 6.5" |
| September | 54°F | 74°F | 63°F | 5.4" |
| October | 44°F | 63°F | 52°F | 4.7" |
| November | 34°F | 51°F | 42°F | 3.8" |
| December | 27°F | 41°F | 33°F | 4.0" |
| Index | Harmony | Pennsylvania | National |
| Air quality index | 31 | 45 | 42 |
| Pollution index | 601,986 | 4,584,805 | 2,726,193 |
| Measurement | Total |
| Days measured | 361 |
| Days with good air quality | 356 |
| Days with moderate air quality | 5 |
| 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. |
| Industry, PA | 1,637 | 6 | 88.0% |
| Bridgewater, PA | 865 | 6 | 88.0% |
| Rochester, PA | 3,468 | 6 | 88.0% |
| Aliquippa, PA | 8,918 | 6 | 88.0% |
| Monaca, PA | 5,466 | 6 | 88.0% |
| Harmony, PA | 1,104 | 31 | 38.0% |
| City | Population | Air Quality Index | National Avg. |
| Archer, FL | 1,104 | 35 | 30.0% |
| Hiawassee, GA | 1,104 | 37 | 26.0% |
| Cavetown, MD | 1,104 | 40 | 20.0% |
| Nashwauk, MN | 1,104 | 35 | 30.0% |
| Gerald, MO | 1,104 | 39 | 22.0% |
| Harmony, PA | 1,104 | 31 | 38.0% |
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