| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 26°F | 41°F | 33°F | 5.8" |
| February | 22°F | 39°F | 30°F | 4.5" |
| March | 28°F | 47°F | 37°F | 6.7" |
| April | 38°F | 58°F | 47°F | 9.1" |
| May | 47°F | 68°F | 57°F | 5.1" |
| June | 60°F | 78°F | 68°F | 1.8" |
| July | 65°F | 82°F | 73°F | 6.2" |
| August | 65°F | 83°F | 74°F | 3.2" |
| September | 57°F | 79°F | 68°F | 3.0" |
| October | 50°F | 67°F | 58°F | 9.6" |
| November | 36°F | 55°F | 46°F | 5.3" |
| December | 28°F | 43°F | 35°F | 6.2" |
| Index | Brookhaven | New York | National |
| Air quality index | 43 | 43 | 42 |
| Pollution index | 39,208,800 | 6,179,275 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 262 |
| Days with moderate air quality | 82 |
| Days w/ poor A.Q. for sensitive groups | 18 |
| Days with unhealthy air quality | 3 |
| Pollutant | Total |
| Arsenic | 0.060% |
| Benzene | 0.320% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.320% |
| Mercury | 0.130% |
| City | Population | Air Quality Index | National Avg. |
| Calverton, NY | 5,280 | 41 | 18.0% |
| Northville village, NY | 1,018 | 41 | 18.0% |
| Riverhead, NY | 13,879 | 41 | 18.0% |
| Westhampton Beach, NY | 1,869 | 41 | 18.0% |
| Northville, NY | 1,607 | 41 | 18.0% |
| Brookhaven, NY | 3,203 | 43 | 14.0% |
| City | Population | Air Quality Index | National Avg. |
| Athens, PA | 3,203 | 36 | 28.0% |
| Coplay, PA | 3,204 | 42 | 16.0% |
| Howe, TX | 3,204 | 325 | 550.0% |
| Beulah, ND | 3,201 | 33 | 34.0% |
| Crockett, CA | 3,205 | 40 | 20.0% |
| Brookhaven, NY | 3,203 | 43 | 14.0% |
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