| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 20°F | 38°F | 28°F | 5.1" |
| February | 20°F | 40°F | 29°F | 3.4" |
| March | 29°F | 50°F | 38°F | 3.8" |
| April | 39°F | 64°F | 51°F | 4.0" |
| May | 49°F | 73°F | 61°F | 4.1" |
| June | 58°F | 80°F | 68°F | 5.3" |
| July | 63°F | 85°F | 73°F | 6.2" |
| August | 60°F | 82°F | 70°F | 5.8" |
| September | 54°F | 76°F | 64°F | 4.5" |
| October | 43°F | 65°F | 53°F | 4.8" |
| November | 33°F | 53°F | 43°F | 2.9" |
| December | 27°F | 43°F | 34°F | 4.8" |
| Index | Hopatcong | New Jersey | National |
| Air quality index | 34 | 45 | 42 |
| Pollution index | 3,291,140 | 7,246,891 | 2,726,193 |
| Measurement | Total |
| Days measured | 349 |
| Days with good air quality | 340 |
| Days with moderate air quality | 9 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.002% |
| Benzene | 0.050% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.020% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Beattystown, NJ | 4,550 | 34 | 32.0% |
| Dover, NJ | 17,866 | 34 | 32.0% |
| Long Valley, NJ | 2,327 | 34 | 32.0% |
| Port Murray, NJ | 216 | 34 | 32.0% |
| Victory Gardens, NJ | 1,604 | 34 | 32.0% |
| Hopatcong, NJ | 14,228 | 34 | 32.0% |
| City | Population | Air Quality Index | National Avg. |
| Lakewood Park, FL | 14,227 | 36 | 28.0% |
| Antioch, IL | 14,231 | 39 | 22.0% |
| North Perth, ON | 14,233 | n/a | |
| Sainte-Adèle, QC | 14,237 | n/a | |
| Greensburg, PA | 14,239 | 56 | 12.0% |
| Hopatcong, NJ | 14,228 | 34 | 32.0% |
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