| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 18°F | 34°F | 26°F | 3.2" |
| February | 18°F | 36°F | 27°F | 3.5" |
| March | 25°F | 44°F | 34°F | 3.5" |
| April | 37°F | 58°F | 47°F | 4.2" |
| May | 48°F | 69°F | 58°F | 3.9" |
| June | 55°F | 76°F | 65°F | 5.6" |
| July | 63°F | 82°F | 72°F | 3.4" |
| August | 61°F | 79°F | 69°F | 5.3" |
| September | 55°F | 73°F | 63°F | 4.1" |
| October | 44°F | 62°F | 52°F | 5.7" |
| November | 33°F | 50°F | 41°F | 3.4" |
| December | 25°F | 40°F | 32°F | 4.8" |
| Index | Westborough | Massachusetts | National |
| Air quality index | 40 | 40 | 42 |
| Pollution index | 14,818,200 | 8,399,610 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 312 |
| Days with moderate air quality | 52 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.020% |
| Benzene | 0.150% |
| Carbon Tetrachloride | 0.050% |
| Lead | 0.130% |
| Mercury | 0.040% |
| City | Population | Air Quality Index | National Avg. |
| Milford, MA | 26,072 | 40 | 20.0% |
| Cordaville, MA | 2,884 | 40 | 20.0% |
| Clinton, MA | 7,058 | 40 | 20.0% |
| Maynard, MA | 10,900 | 40 | 20.0% |
| East Douglas, MA | 2,985 | 40 | 20.0% |
| Westborough, MA | 4,024 | 40 | 20.0% |
| City | Population | Air Quality Index | National Avg. |
| Caro, MI | 4,024 | 26 | 48.0% |
| Ellenville, NY | 4,024 | 36 | 28.0% |
| Bluffton, OH | 4,024 | 39 | 22.0% |
| Saint-Ambroise-de-Kildare, QC | 4,024 | n/a | |
| Meridian, PA | 4,023 | 31 | 38.0% |
| Westborough, MA | 4,024 | 40 | 20.0% |
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