| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 19°F | 38°F | 28°F | 3.1" |
| February | 19°F | 39°F | 29°F | 2.9" |
| March | 28°F | 48°F | 38°F | 3.8" |
| April | 38°F | 61°F | 49°F | 3.7" |
| May | 47°F | 71°F | 59°F | 3.8" |
| June | 57°F | 78°F | 67°F | 4.7" |
| July | 62°F | 84°F | 73°F | 5.0" |
| August | 60°F | 81°F | 70°F | 4.8" |
| September | 53°F | 76°F | 64°F | 4.2" |
| October | 43°F | 65°F | 53°F | 4.4" |
| November | 32°F | 53°F | 42°F | 3.0" |
| December | 25°F | 43°F | 34°F | 4.8" |
| Index | Ridgefield | Connecticut | National |
| Air quality index | 43 | 43 | 42 |
| Pollution index | 16,950,700 | 8,629,883 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 262 |
| Days with moderate air quality | 82 |
| Days w/ poor A.Q. for sensitive groups | 18 |
| Days with unhealthy air quality | 3 |
| Pollutant | Total |
| Arsenic | 0.030% |
| Benzene | 0.140% |
| Carbon Tetrachloride | 0.070% |
| Lead | 0.080% |
| Mercury | 0.030% |
| City | Population | Air Quality Index | National Avg. |
| Heritage Hills, NY | 4,309 | 36 | 28.0% |
| Yorktown Heights, NY | 1,567 | 36 | 28.0% |
| Carmel Hamlet, NY | 6,278 | 36 | 28.0% |
| Lincolndale, NY | 1,407 | 36 | 28.0% |
| Lake Carmel, NY | 8,287 | 36 | 28.0% |
| Ridgefield, CT | 7,228 | 43 | 14.0% |
| City | Population | Air Quality Index | National Avg. |
| Stanwood, WA | 7,228 | 24 | 52.0% |
| Wauseon, OH | 7,229 | 39 | 22.0% |
| Otonabee-South Monaghan, ON | 7,229 | n/a | |
| Canfield, OH | 7,226 | 42 | 16.0% |
| Rocky Mountain House, AB | 7,226 | n/a | |
| Ridgefield, CT | 7,228 | 43 | 14.0% |
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