| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 23°F | 39°F | 31°F | 5.1" |
| February | 21°F | 37°F | 29°F | 3.7" |
| March | 26°F | 44°F | 36°F | 7.9" |
| April | 36°F | 55°F | 46°F | 10.1" |
| May | 46°F | 65°F | 55°F | 5.8" |
| June | 57°F | 75°F | 65°F | 4.6" |
| July | 62°F | 80°F | 70°F | 3.4" |
| August | 63°F | 81°F | 71°F | 4.1" |
| September | 57°F | 76°F | 66°F | 5.3" |
| October | 49°F | 65°F | 56°F | 9.3" |
| November | 35°F | 54°F | 45°F | 6.2" |
| December | 26°F | 41°F | 33°F | 5.6" |
| Index | Westerly | Rhode Island | National |
| Air quality index | 37 | 45 | 42 |
| Pollution index | 2,960,790 | 3,440,259 | 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 | 0.003% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.020% |
| Mercury | 0.005% |
| City | Population | Air Quality Index | National Avg. |
| Norwich, CT | 39,112 | 37 | 26.0% |
| Hopkinton, RI | 612 | 37 | 26.0% |
| Gales Ferry, CT | 1,093 | 37 | 26.0% |
| Bradford, RI | 1,265 | 37 | 26.0% |
| New London, CT | 27,001 | 37 | 26.0% |
| Westerly, RI | 17,842 | 37 | 26.0% |
| City | Population | Air Quality Index | National Avg. |
| Radford, VA | 17,833 | 41 | 18.0% |
| Jenison, MI | 17,851 | 38 | 24.0% |
| El Dorado, AR | 17,826 | 35 | 30.0% |
| Canby, OR | 17,860 | 38 | 24.0% |
| Amsterdam, NY | 17,823 | 37 | 26.0% |
| Westerly, RI | 17,842 | 37 | 26.0% |
Here are the best places to live in Rhode Island
See the best places to live in Westerly
Check out the 10 most dangerous cities in Rhode Island
Safest States In The US