| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 24°F | 39°F | 31°F | 6.8" |
| February | 23°F | 39°F | 30°F | 6.4" |
| March | 29°F | 46°F | 37°F | 7.5" |
| April | 38°F | 56°F | 47°F | 9.7" |
| May | 48°F | 65°F | 56°F | 6.2" |
| June | 58°F | 73°F | 65°F | 8.0" |
| July | 64°F | 79°F | 72°F | 9.7" |
| August | 62°F | 77°F | 69°F | 9.2" |
| September | 55°F | 70°F | 62°F | 14.3" |
| October | 45°F | 61°F | 53°F | 4.9" |
| November | 38°F | 52°F | 45°F | 10.3" |
| December | 28°F | 44°F | 36°F | 7.1" |
| Index | Onset | Massachusetts | National |
| Air quality index | 36 | 40 | 42 |
| Pollution index | 9,737,620 | 8,399,610 | 2,726,193 |
| Measurement | Total |
| Days measured | 359 |
| Days with good air quality | 348 |
| Days with moderate air quality | 11 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.180% |
| Benzene | 0.070% |
| Carbon Tetrachloride | 0.040% |
| Lead | 0.170% |
| Mercury | 0.140% |
| City | Population | Air Quality Index | National Avg. |
| Plymouth, MA | 6,949 | 36 | 28.0% |
| East Falmouth, MA | 6,163 | 36 | 28.0% |
| Mattapoisett Center, MA | 3,193 | 36 | 28.0% |
| North Falmouth, MA | 2,572 | 36 | 28.0% |
| Popponesset Island, MA | 35 | 36 | 28.0% |
| Onset, MA | 1,049 | 36 | 28.0% |
| City | Population | Air Quality Index | National Avg. |
| Skyline, AL | 1,049 | 44 | 12.0% |
| Herald, CA | 1,049 | 45 | 10.0% |
| Saybrook Manor, CT | 1,049 | 37 | 26.0% |
| Canon, GA | 1,049 | 41 | 18.0% |
| Tyrone, OK | 1,049 | 15 | 70.0% |
| Onset, MA | 1,049 | 36 | 28.0% |
Here are the best places to live in Massachusetts
Most Dangerous Cities In The US
Check out the 10 most dangerous cities in Massachusetts
See the best places to live in Onset