| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 20°F | 39°F | 29°F | 2.9" |
| February | 20°F | 40°F | 30°F | 2.5" |
| March | 30°F | 53°F | 40°F | 3.3" |
| April | 40°F | 66°F | 53°F | 3.2" |
| May | 49°F | 75°F | 62°F | 4.1" |
| June | 59°F | 82°F | 70°F | 4.3" |
| July | 62°F | 85°F | 73°F | 4.5" |
| August | 61°F | 84°F | 72°F | 3.5" |
| September | 54°F | 78°F | 66°F | 3.0" |
| October | 44°F | 66°F | 54°F | 3.6" |
| November | 33°F | 55°F | 43°F | 2.6" |
| December | 26°F | 43°F | 34°F | 3.6" |
| Index | Heidelberg | Pennsylvania | National |
| Air quality index | 56 | 45 | 42 |
| Pollution index | 2,548,030 | 4,584,805 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 129 |
| Days with moderate air quality | 220 |
| Days w/ poor A.Q. for sensitive groups | 12 |
| Days with unhealthy air quality | 4 |
| Pollutant | Total |
| Arsenic | 0.220% |
| Benzene | 0.040% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.050% |
| Mercury | 0.020% |
| City | Population | Air Quality Index | National Avg. |
| Bulger, PA | 412 | 46 | 8.0% |
| Wolfdale, PA | 3,097 | 46 | 8.0% |
| Hickory, PA | 542 | 46 | 8.0% |
| Clinton, PA | 1,049 | 46 | 8.0% |
| Westland, PA | 45 | 46 | 8.0% |
| Heidelberg, PA | 1,228 | 56 | 12.0% |
| City | Population | Air Quality Index | National Avg. |
| Manton, MI | 1,228 | 36 | 28.0% |
| Cinnamon Lake, OH | 1,228 | 43 | 14.0% |
| Lot 15, PE | 1,228 | n/a | |
| Naujaat, NU | 1,228 | n/a | |
| Forkland, AL | 1,229 | 35 | 30.0% |
| Heidelberg, PA | 1,228 | 56 | 12.0% |
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