| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 23°F | 40°F | 31°F | 3.2" |
| February | 22°F | 41°F | 31°F | 3.2" |
| March | 29°F | 48°F | 38°F | 3.8" |
| April | 40°F | 61°F | 49°F | 3.7" |
| May | 50°F | 69°F | 58°F | 3.8" |
| June | 59°F | 78°F | 67°F | 4.7" |
| July | 66°F | 85°F | 74°F | 4.1" |
| August | 64°F | 83°F | 73°F | 3.5" |
| September | 58°F | 77°F | 66°F | 3.0" |
| October | 48°F | 66°F | 56°F | 5.0" |
| November | 37°F | 55°F | 45°F | 3.3" |
| December | 28°F | 45°F | 36°F | 4.6" |
| Index | Chelsea | Massachusetts | National |
| Air quality index | 43 | 40 | 42 |
| Pollution index | 24,018,000 | 8,399,610 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 291 |
| Days with moderate air quality | 73 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.030% |
| Benzene | 0.220% |
| Carbon Tetrachloride | 0.100% |
| Lead | 0.280% |
| Mercury | 0.130% |
| City | Population | Air Quality Index | National Avg. |
| Dover, MA | 2,518 | 43 | 14.0% |
| Milton, MA | 27,590 | 43 | 14.0% |
| Norwood, MA | 29,446 | 43 | 14.0% |
| Beverly, MA | 42,062 | 43 | 14.0% |
| Arlington, MA | 45,379 | 43 | 14.0% |
| Chelsea, MA | 39,878 | 43 | 14.0% |
| City | Population | Air Quality Index | National Avg. |
| The Acreage, FL | 39,863 | 36 | 28.0% |
| Friendswood, TX | 39,893 | 52 | 4.0% |
| Marion, IA | 39,910 | 39 | 22.0% |
| Calexico, CA | 39,841 | 58 | 16.0% |
| Streamwood, IL | 39,917 | 55 | 10.0% |
| Chelsea, MA | 39,878 | 43 | 14.0% |
Here are the best places to live in Massachusetts
These are the 10 cheapest cities in Massachusetts
See the best places to live in Chelsea
Check out the 10 most dangerous cities in Massachusetts