| 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 | Annex | New Haven | Connecticut |
| Air quality index | 41 | 41 | 43 |
| Pollution index | 14,500,300 | 14,500,300 | 8,629,883 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 280 |
| Days with moderate air quality | 71 |
| Days w/ poor A.Q. for sensitive groups | 12 |
| Days with unhealthy air quality | 2 |
| Pollutant | Total |
| Arsenic | 0.030% |
| Benzene | 0.140% |
| Carbon Tetrachloride | 0.050% |
| Lead | 0.080% |
| Mercury | 0.060% |
| City | Population | Air Quality Index | National Avg. |
| Durham, CT | 3,542 | 41 | 18.0% |
| Derby, CT | 12,420 | 41 | 18.0% |
| East Haven, CT | 28,645 | 41 | 18.0% |
| Naugatuck, CT | 31,201 | 41 | 18.0% |
| Shelton, CT | 41,162 | 41 | 18.0% |
| New Haven, CT | 130,381 | 41 | 18.0% |
| City | Population | Air Quality Index | National Avg. |
| Stamford, CT | 130,057 | 43 | 14.0% |
| Kent, WA | 130,038 | 45 | 10.0% |
| Concord, CA | 129,227 | 40 | 20.0% |
| Round Rock, TX | 128,812 | 44 | 12.0% |
| Langley, BC | 132,088 | n/a | |
| New Haven, CT | 130,381 | 41 | 18.0% |
Here are the best places to live in Connecticut
Check out the 10 safest cities in Connecticut
These are the 10 most affordable cities in Connecticut
Top 10 cities in Connecticut with the best education system