| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 22°F | 38°F | 29°F | 6.3" |
| February | 20°F | 38°F | 29°F | 6.1" |
| March | 28°F | 47°F | 37°F | 8.2" |
| April | 39°F | 59°F | 48°F | 7.7" |
| May | 48°F | 69°F | 58°F | 6.4" |
| June | 56°F | 76°F | 65°F | 7.2" |
| July | 63°F | 82°F | 72°F | 10.6" |
| August | 60°F | 80°F | 69°F | 9.0" |
| September | 54°F | 73°F | 63°F | 8.3" |
| October | 44°F | 63°F | 53°F | 7.9" |
| November | 35°F | 52°F | 43°F | 8.0" |
| December | 27°F | 42°F | 34°F | 7.8" |
| Index | Harmony | Rhode Island | National |
| Air quality index | 44 | 45 | 42 |
| Pollution index | 8,312,000 | 3,440,259 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 289 |
| Days with moderate air quality | 74 |
| Days w/ poor A.Q. for sensitive groups | 2 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.090% |
| Carbon Tetrachloride | 0.040% |
| Lead | 0.210% |
| Mercury | 0.060% |
| City | Population | Air Quality Index | National Avg. |
| Putnam, CT | 7,138 | 33 | 34.0% |
| Danielson, CT | 3,996 | 33 | 34.0% |
| Moosup, CT | 3,922 | 37 | 26.0% |
| Oxford, MA | 5,926 | 40 | 20.0% |
| Webster, MA | 11,719 | 40 | 20.0% |
| Harmony, RI | 1,195 | 44 | 12.0% |
| City | Population | Air Quality Index | National Avg. |
| Ponderay, ID | 1,195 | 43 | 14.0% |
| Stiles, PA | 1,195 | 42 | 16.0% |
| Iola, WI | 1,195 | 37 | 26.0% |
| Glenella-Lansdowne, MB | 1,195 | n/a | |
| Lake Park, IA | 1,194 | 36 | 28.0% |
| Harmony, RI | 1,195 | 44 | 12.0% |
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