| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 26°F | 43°F | 34°F | 3.7" |
| February | 26°F | 45°F | 35°F | 2.7" |
| March | 34°F | 54°F | 43°F | 3.7" |
| April | 44°F | 67°F | 55°F | 4.3" |
| May | 53°F | 76°F | 64°F | 4.2" |
| June | 63°F | 84°F | 74°F | 4.7" |
| July | 69°F | 89°F | 79°F | 5.0" |
| August | 67°F | 86°F | 76°F | 4.9" |
| September | 60°F | 81°F | 70°F | 4.1" |
| October | 49°F | 69°F | 58°F | 4.9" |
| November | 38°F | 58°F | 48°F | 3.0" |
| December | 32°F | 48°F | 39°F | 4.8" |
| Index | Langhorne | Pennsylvania | National |
| Air quality index | 41 | 45 | 42 |
| Pollution index | 8,206,310 | 4,584,805 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 280 |
| Days with moderate air quality | 83 |
| Days w/ poor A.Q. for sensitive groups | 2 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.260% |
| Benzene | 0.060% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.160% |
| Mercury | 1.120% |
| City | Population | Air Quality Index | National Avg. |
| Lambertville, NJ | 3,809 | 41 | 18.0% |
| Florence, NJ | 4,455 | 41 | 18.0% |
| Croydon, PA | 9,693 | 41 | 18.0% |
| Penndel, PA | 2,928 | 41 | 18.0% |
| Lawrenceville, NJ | 3,515 | 41 | 18.0% |
| Langhorne, PA | 1,616 | 41 | 18.0% |
| City | Population | Air Quality Index | National Avg. |
| Port Gibson, MS | 1,616 | 44 | 12.0% |
| Cleora, OK | 1,616 | 38 | 24.0% |
| De Kalb, TX | 1,616 | 39 | 22.0% |
| Samson, AL | 1,615 | 35 | 30.0% |
| Royal Palm Estates, FL | 1,615 | 36 | 28.0% |
| Langhorne, PA | 1,616 | 41 | 18.0% |
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