| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 18°F | 38°F | 28°F | 3.3" |
| February | 18°F | 40°F | 29°F | 3.6" |
| March | 26°F | 50°F | 38°F | 3.6" |
| April | 37°F | 65°F | 50°F | 4.0" |
| May | 47°F | 75°F | 60°F | 4.0" |
| June | 57°F | 82°F | 69°F | 5.5" |
| July | 63°F | 88°F | 75°F | 4.9" |
| August | 60°F | 86°F | 72°F | 4.9" |
| September | 54°F | 80°F | 66°F | 3.9" |
| October | 43°F | 67°F | 54°F | 5.9" |
| November | 32°F | 55°F | 43°F | 3.2" |
| December | 24°F | 44°F | 33°F | 4.5" |
| Index | Thompsonville | Connecticut | National |
| Air quality index | 40 | 43 | 42 |
| Pollution index | 7,859,360 | 8,629,883 | 2,726,193 |
| Measurement | Total |
| Days measured | 364 |
| Days with good air quality | 305 |
| Days with moderate air quality | 59 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.030% |
| Benzene | 0.070% |
| Carbon Tetrachloride | 0.030% |
| Lead | 0.320% |
| Mercury | 0.070% |
| City | Population | Air Quality Index | National Avg. |
| Coventry Lake, CT | 2,135 | 33 | 34.0% |
| Crystal Lake, CT | 2,567 | 40 | 20.0% |
| Somers, CT | 2,343 | 40 | 20.0% |
| Agawam Town, MA | 28,627 | 40 | 20.0% |
| Chicopee, MA | 55,186 | 40 | 20.0% |
| Thompsonville, CT | 8,563 | 40 | 20.0% |
| City | Population | Air Quality Index | National Avg. |
| Lake of the Woods, VA | 8,565 | 40 | 20.0% |
| Monroe, NY | 8,567 | 36 | 28.0% |
| Sitka, AK | 8,569 | 20 | 60.0% |
| Boischatel, QC | 8,556 | n/a | |
| Hoquiam, WA | 8,570 | 20 | 60.0% |
| Thompsonville, CT | 8,563 | 40 | 20.0% |
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