| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 15°F | 32°F | 23°F | 4.4" |
| February | 12°F | 33°F | 22°F | 4.1" |
| March | 18°F | 41°F | 30°F | 5.1" |
| April | 33°F | 55°F | 44°F | 12.8" |
| May | 43°F | 66°F | 54°F | 6.8" |
| June | 55°F | 78°F | 66°F | 4.6" |
| July | 59°F | 80°F | 69°F | 5.1" |
| August | 58°F | 80°F | 69°F | 3.2" |
| September | 51°F | 75°F | 62°F | 3.5" |
| October | 43°F | 61°F | 52°F | 7.2" |
| November | 28°F | 47°F | 37°F | 6.3" |
| December | 16°F | 33°F | 25°F | 5.9" |
| Index | Winchendon | Massachusetts | National |
| Air quality index | 34 | 40 | 42 |
| Pollution index | 6,602,810 | 8,399,610 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 348 |
| Days with moderate air quality | 17 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.070% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.060% |
| Mercury | 0.010% |
| City | Population | Air Quality Index | National Avg. |
| Troy, NH | 879 | 34 | 32.0% |
| West Swanzey, NH | 1,204 | 34 | 32.0% |
| Athol, MA | 8,568 | 34 | 32.0% |
| Jaffrey, NH | 2,852 | 34 | 32.0% |
| Baldwinville, MA | 2,181 | 34 | 32.0% |
| Winchendon, MA | 4,851 | 34 | 32.0% |
| City | Population | Air Quality Index | National Avg. |
| Saint-Agapit, QC | 4,850 | n/a | |
| Fraser-Fort George D, BC | 4,848 | n/a | |
| Farmville, NC | 4,854 | 38 | 24.0% |
| Edwardsville, PA | 4,854 | 38 | 24.0% |
| Auburn, IL | 4,846 | 40 | 20.0% |
| Winchendon, MA | 4,851 | 34 | 32.0% |