| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 23°F | 40°F | 32°F | 2.6" |
| February | 23°F | 41°F | 32°F | 2.8" |
| March | 30°F | 48°F | 39°F | 3.4" |
| April | 40°F | 60°F | 50°F | 4.5" |
| May | 50°F | 69°F | 59°F | 3.8" |
| June | 60°F | 78°F | 68°F | 4.7" |
| July | 66°F | 84°F | 75°F | 3.1" |
| August | 64°F | 82°F | 74°F | 3.7" |
| September | 58°F | 77°F | 67°F | 3.2" |
| October | 47°F | 66°F | 57°F | 4.5" |
| November | 37°F | 55°F | 46°F | 2.9" |
| December | 30°F | 45°F | 37°F | 4.2" |
| Index | West Haven | Connecticut | National |
| Air quality index | 49 | 43 | 50 |
| Pollution index | 14,500,300 | 7,127,531 | 5,066,862 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 194 |
| Days with moderate air quality | 161 |
| Days w/ poor A.Q. for sensitive groups | 10 |
| Days with unhealthy air quality |
| Pollutant | Total |
| Arsenic | 0.030% |
| Benzene | 0.140% |
| Carbon Tetrachloride | 0.050% |
| Lead | 0.080% |
| Mercury | 0.060% |
| City, State | Population | Air Quality Index | National Avg. |
| Stratford, CT | 52,300 | 47 | 6% |
| Bridgeport, CT | 147,022 | 47 | 6% |
| Trumbull, CT | 36,477 | 47 | 6% |
| Milford city, CT | 52,005 | 47 | 6% |
| Ansonia, CT | 18,950 | 49 | 2% |
| West Haven, CT | 54,972 | 49 | 2% |
| City, State | Population | Air Quality Index | National Avg. |
| Paramount, CA | 54,941 | 74 | 48% |
| Shoreline, WA | 55,021 | 49 | 2% |
| Port Arthur, TX | 54,913 | 44 | 12% |
| Hanford, CA | 54,912 | 68 | 36% |
| Aloha, OR | 54,908 | 38 | 24% |
| West Haven, CT | 54,972 | 49 | 2% |