| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 20°F | 38°F | 29°F | 2.4" |
| February | 20°F | 40°F | 30°F | 1.9" |
| March | 29°F | 51°F | 39°F | 2.6" |
| April | 39°F | 65°F | 52°F | 3.4" |
| May | 49°F | 75°F | 61°F | 3.8" |
| June | 59°F | 83°F | 71°F | 3.9" |
| July | 62°F | 86°F | 74°F | 4.7" |
| August | 60°F | 84°F | 71°F | 4.2" |
| September | 53°F | 78°F | 64°F | 4.4" |
| October | 43°F | 66°F | 53°F | 4.5" |
| November | 32°F | 54°F | 42°F | 3.0" |
| December | 26°F | 43°F | 34°F | 3.2" |
| Index | Herndon | Pennsylvania | National |
| Air quality index | 44 | 45 | 42 |
| Pollution index | 3,637,020 | 4,584,805 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 252 |
| Days with moderate air quality | 107 |
| Days w/ poor A.Q. for sensitive groups | 5 |
| Days with unhealthy air quality | 1 |
| Pollutant | Total |
| Arsenic | 0.020% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.004% |
| Lead | 0.010% |
| Mercury | 0.002% |
| City | Population | Air Quality Index | National Avg. |
| Kratzerville, PA | 336 | 35 | 30.0% |
| Penns Creek, PA | 507 | 35 | 30.0% |
| Freeburg, PA | 793 | 35 | 30.0% |
| Mifflinburg, PA | 3,493 | 35 | 30.0% |
| Kreamer, PA | 655 | 35 | 30.0% |
| Herndon, PA | 374 | 44 | 12.0% |
| City | Population | Air Quality Index | National Avg. |
| Potter Valley, CA | 374 | 33 | 34.0% |
| Mondamin, IA | 374 | 40 | 20.0% |
| Eden, ID | 374 | 20 | 60.0% |
| Marshall, IN | 374 | 45 | 10.0% |
| Sylvan Grove, KS | 374 | 32 | 36.0% |
| Herndon, PA | 374 | 44 | 12.0% |
Here are the best places to live in Pennsylvania
Check out the 10 most dangerous cities in Pennsylvania
Most Dangerous Cities In The US
These are the largest cities in Pennsylvania