| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 22°F | 42°F | 32°F | 3.4" |
| February | 23°F | 44°F | 33°F | 3.1" |
| March | 33°F | 57°F | 44°F | 4.6" |
| April | 43°F | 69°F | 56°F | 5.0" |
| May | 52°F | 77°F | 64°F | 4.0" |
| June | 61°F | 85°F | 73°F | 5.2" |
| July | 65°F | 87°F | 76°F | 4.0" |
| August | 64°F | 88°F | 76°F | 3.0" |
| September | 57°F | 81°F | 69°F | 4.1" |
| October | 45°F | 69°F | 57°F | 4.1" |
| November | 34°F | 57°F | 45°F | 3.5" |
| December | 27°F | 45°F | 36°F | 4.5" |
| Index | St. Leon | Indiana | National |
| Air quality index | 54 | 56 | 42 |
| Pollution index | 2,686,940 | 2,719,453 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 139 |
| Days with moderate air quality | 206 |
| Days w/ poor A.Q. for sensitive groups | 20 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.040% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.110% |
| Mercury | 0.010% |
| City | Population | Air Quality Index | National Avg. |
| Brookville, IN | 2,535 | 6 | 88.0% |
| Oldenburg, IN | 629 | 6 | 88.0% |
| Metamora, IN | 410 | 6 | 88.0% |
| Laurel, IN | 778 | 6 | 88.0% |
| Oxford, OH | 23,192 | 6 | 88.0% |
| St. Leon, IN | 1,041 | 54 | 8.0% |
| City | Population | Air Quality Index | National Avg. |
| Poncha Springs, CO | 1,041 | 16 | 68.0% |
| Cloverport, KY | 1,041 | 43 | 14.0% |
| Kraemer, LA | 1,041 | 41 | 18.0% |
| Norwood Court, MO | 1,041 | 54 | 8.0% |
| Marion, MT | 1,041 | 37 | 26.0% |
| St. Leon, IN | 1,041 | 54 | 8.0% |
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