| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 19°F | 34°F | 26°F | 4.3" |
| February | 19°F | 36°F | 27°F | 4.1" |
| March | 32°F | 51°F | 41°F | 5.8" |
| April | 41°F | 65°F | 52°F | 7.7" |
| May | 52°F | 74°F | 63°F | 7.7" |
| June | 61°F | 82°F | 72°F | 10.1" |
| July | 64°F | 84°F | 74°F | 6.8" |
| August | 62°F | 83°F | 72°F | 10.2" |
| September | 55°F | 77°F | 66°F | 6.2" |
| October | 44°F | 66°F | 54°F | 5.8" |
| November | 33°F | 52°F | 42°F | 6.4" |
| December | 24°F | 39°F | 31°F | 4.7" |
| Index | Roann | Indiana | National |
| Air quality index | 37 | 56 | 42 |
| Pollution index | 1,806,400 | 2,719,453 | 2,726,193 |
| Measurement | Total |
| Days measured | 351 |
| Days with good air quality | 319 |
| Days with moderate air quality | 32 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.030% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.100% |
| Mercury | 0.010% |
| City | Population | Air Quality Index | National Avg. |
| Sidney, IN | 66 | 31 | 38.0% |
| Onward, IN | 177 | 37 | 26.0% |
| Wabash, IN | 10,243 | 37 | 26.0% |
| North Manchester, IN | 5,814 | 37 | 26.0% |
| Silver Lake, IN | 1,090 | 37 | 26.0% |
| Roann, IN | 347 | 37 | 26.0% |
| City | Population | Air Quality Index | National Avg. |
| St. Charles, AR | 347 | 43 | 14.0% |
| McIntosh, FL | 347 | 35 | 30.0% |
| Letts, IA | 347 | 32 | 36.0% |
| Brocton, IL | 347 | 42 | 16.0% |
| Greeley County, KS | 347 | 15 | 70.0% |
| Roann, IN | 347 | 37 | 26.0% |