| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 25°F | 42°F | 33°F | 4.2" |
| February | 25°F | 43°F | 34°F | 3.6" |
| March | 33°F | 52°F | 42°F | 3.9" |
| April | 44°F | 66°F | 54°F | 4.4" |
| May | 53°F | 75°F | 63°F | 4.9" |
| June | 63°F | 84°F | 72°F | 5.3" |
| July | 69°F | 89°F | 78°F | 4.5" |
| August | 66°F | 86°F | 76°F | 5.0" |
| September | 60°F | 81°F | 69°F | 3.5" |
| October | 49°F | 69°F | 58°F | 4.8" |
| November | 38°F | 58°F | 47°F | 3.1" |
| December | 31°F | 47°F | 38°F | 5.0" |
| Index | Closter | New Jersey | National |
| Air quality index | 51 | 45 | 42 |
| Pollution index | 7,043,200 | 7,246,891 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 169 |
| Days with moderate air quality | 180 |
| Days w/ poor A.Q. for sensitive groups | 16 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.050% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.030% |
| Mercury | 0.020% |
| City | Population | Air Quality Index | National Avg. |
| Pomona, NY | 3,058 | 36 | 28.0% |
| Rye Brook, NY | 9,554 | 43 | 14.0% |
| Armonk, NY | 4,440 | 43 | 14.0% |
| Pleasantville, NY | 7,256 | 43 | 14.0% |
| Thornwood, NY | 4,484 | 43 | 14.0% |
| Closter, NJ | 8,551 | 51 | 2.0% |
| City | Population | Air Quality Index | National Avg. |
| Frostburg, MD | 8,550 | 36 | 28.0% |
| Woodbury CDP, NY | 8,549 | 36 | 28.0% |
| Rapid Valley, SD | 8,553 | 44 | 12.0% |
| Hornsby Bend, TX | 8,553 | 44 | 12.0% |
| East Grand Forks, MN | 8,555 | 33 | 34.0% |
| Closter, NJ | 8,551 | 51 | 2.0% |
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