| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 23°F | 40°F | 31°F | 3.0" |
| February | 23°F | 42°F | 32°F | 2.9" |
| March | 31°F | 52°F | 41°F | 3.5" |
| April | 42°F | 65°F | 52°F | 3.9" |
| May | 51°F | 74°F | 62°F | 4.0" |
| June | 60°F | 82°F | 71°F | 4.9" |
| July | 66°F | 87°F | 76°F | 4.9" |
| August | 63°F | 84°F | 73°F | 4.9" |
| September | 57°F | 78°F | 67°F | 3.7" |
| October | 46°F | 67°F | 56°F | 4.2" |
| November | 36°F | 55°F | 45°F | 2.8" |
| December | 29°F | 45°F | 36°F | 4.4" |
| Index | Chatham | New Jersey | National |
| Air quality index | 51 | 45 | 42 |
| Pollution index | 12,837,200 | 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 | 0.110% |
| Carbon Tetrachloride | 0.050% |
| Lead | 0.020% |
| Mercury | 0.230% |
| City | Population | Air Quality Index | National Avg. |
| Hopatcong, NJ | 14,228 | 34 | 32.0% |
| Victory Gardens, NJ | 1,604 | 34 | 32.0% |
| Mendham, NJ | 4,880 | 34 | 32.0% |
| Kenvil, NJ | 1,934 | 34 | 32.0% |
| Wharton, NJ | 6,458 | 34 | 32.0% |
| Chatham, NJ | 8,729 | 51 | 2.0% |
| City | Population | Air Quality Index | National Avg. |
| Cortez, CO | 8,729 | 44 | 12.0% |
| Brigantine, NJ | 8,725 | 37 | 26.0% |
| Swissvale, PA | 8,724 | 56 | 12.0% |
| New Albany, MS | 8,723 | 39 | 22.0% |
| Park Ridge, NJ | 8,721 | 51 | 2.0% |
| Chatham, NJ | 8,729 | 51 | 2.0% |
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