| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 21°F | 39°F | 30°F | 2.9" |
| February | 21°F | 40°F | 31°F | 3.1" |
| March | 29°F | 49°F | 39°F | 3.5" |
| April | 40°F | 63°F | 51°F | 4.2" |
| May | 50°F | 73°F | 61°F | 3.8" |
| June | 60°F | 81°F | 70°F | 5.1" |
| July | 66°F | 86°F | 76°F | 4.5" |
| August | 64°F | 84°F | 73°F | 4.1" |
| September | 57°F | 78°F | 67°F | 3.5" |
| October | 46°F | 66°F | 55°F | 5.2" |
| November | 35°F | 54°F | 44°F | 3.3" |
| December | 27°F | 43°F | 35°F | 4.2" |
| Index | West Hartford | Connecticut | National |
| Air quality index | 41 | 43 | 42 |
| Pollution index | 2,806,150 | 8,629,883 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 291 |
| Days with moderate air quality | 66 |
| Days w/ poor A.Q. for sensitive groups | 7 |
| Days with unhealthy air quality | 1 |
| Pollutant | Total |
| Arsenic | 0.004% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.040% |
| Mercury | 0.010% |
| City | Population | Air Quality Index | National Avg. |
| Terryville, CT | 5,019 | 37 | 26.0% |
| Collinsville, CT | 3,729 | 37 | 26.0% |
| Bristol, CT | 60,039 | 37 | 26.0% |
| New Hartford Center, CT | 1,210 | 37 | 26.0% |
| Southwood Acres, CT | 8,352 | 40 | 20.0% |
| West Hartford, CT | 63,023 | 41 | 18.0% |
| City | Population | Air Quality Index | National Avg. |
| Brentwood, CA | 63,013 | 45 | 10.0% |
| Encinitas, CA | 62,967 | 64 | 28.0% |
| La Habra, CA | 62,787 | 72 | 44.0% |
| Skokie, IL | 63,300 | 55 | 10.0% |
| Brentwood, NY | 62,743 | 43 | 14.0% |
| West Hartford, CT | 63,023 | 41 | 18.0% |
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