| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 26°F | 40°F | 32°F | 2.8" |
| February | 26°F | 42°F | 34°F | 3.1" |
| March | 34°F | 53°F | 43°F | 5.7" |
| April | 44°F | 64°F | 54°F | 6.3" |
| May | 52°F | 72°F | 62°F | 4.9" |
| June | 63°F | 81°F | 72°F | 6.5" |
| July | 67°F | 85°F | 77°F | 5.8" |
| August | 66°F | 84°F | 75°F | 4.1" |
| September | 59°F | 78°F | 69°F | 3.2" |
| October | 48°F | 65°F | 57°F | 6.4" |
| November | 40°F | 55°F | 48°F | 2.5" |
| December | 29°F | 42°F | 35°F | 3.6" |
| Index | Horsham | Pennsylvania | National |
| Air quality index | 51 | 45 | 42 |
| Pollution index | 8,206,310 | 4,584,805 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 180 |
| Days with moderate air quality | 169 |
| Days w/ poor A.Q. for sensitive groups | 16 |
| 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. |
| Plumsteadville, PA | 2,286 | 41 | 18.0% |
| Langhorne Manor, PA | 1,491 | 41 | 18.0% |
| Newtown Grant, PA | 5,740 | 41 | 18.0% |
| Doylestown, PA | 8,282 | 41 | 18.0% |
| Penndel, PA | 2,928 | 41 | 18.0% |
| Horsham, PA | 15,864 | 51 | 2.0% |
| City | Population | Air Quality Index | National Avg. |
| River Falls, WI | 15,870 | 37 | 26.0% |
| South River, NJ | 15,874 | 41 | 18.0% |
| New Territory, TX | 15,843 | 52 | 4.0% |
| Bellmore, NY | 15,887 | 51 | 2.0% |
| North Decatur, GA | 15,833 | 52 | 4.0% |
| Horsham, PA | 15,864 | 51 | 2.0% |
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