| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 23°F | 40°F | 32°F | 2.5" |
| February | 23°F | 40°F | 32°F | 2.1" |
| March | 30°F | 47°F | 38°F | 3.3" |
| April | 39°F | 58°F | 48°F | 3.1" |
| May | 48°F | 66°F | 57°F | 3.6" |
| June | 58°F | 75°F | 66°F | 3.6" |
| July | 65°F | 81°F | 72°F | 2.8" |
| August | 63°F | 80°F | 71°F | 3.0" |
| September | 57°F | 75°F | 66°F | 3.3" |
| October | 47°F | 65°F | 56°F | 4.4" |
| November | 37°F | 55°F | 46°F | 2.9" |
| December | 29°F | 46°F | 37°F | 3.4" |
| Index | Niantic | Connecticut | National |
| Air quality index | 37 | 43 | 42 |
| Pollution index | 4,117,250 | 8,629,883 | 2,726,193 |
| Measurement | Total |
| Days measured | 364 |
| Days with good air quality | 323 |
| Days with moderate air quality | 34 |
| Days w/ poor A.Q. for sensitive groups | 7 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.050% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.010% |
| Mercury | 0.010% |
| City | Population | Air Quality Index | National Avg. |
| Fishers Island, NY | 61 | 37 | 26.0% |
| Mashantucket, CT | 225 | 37 | 26.0% |
| Conning Towers Nautilus Park, CT | 9,606 | 37 | 26.0% |
| Fenwick, CT | 44 | 37 | 26.0% |
| Old Saybrook Center, CT | 1,984 | 37 | 26.0% |
| Niantic, CT | 3,083 | 37 | 26.0% |
| City | Population | Air Quality Index | National Avg. |
| Wilder, KY | 3,083 | 54 | 8.0% |
| Calera, OK | 3,082 | 325 | 550.0% |
| Thurso, QC | 3,084 | n/a | |
| Bishop, TX | 3,085 | 30 | 40.0% |
| Chandler, TX | 3,085 | 36 | 28.0% |
| Niantic, CT | 3,083 | 37 | 26.0% |
Here are the best places to live in Connecticut
Check out the 10 safest cities in Connecticut
See the best places to live in Niantic
These are the 10 cheapest cities in Connecticut