| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 27°F | 43°F | 35°F | 7.9" |
| February | 20°F | 40°F | 29°F | 3.7" |
| March | 33°F | 56°F | 43°F | 5.0" |
| April | 40°F | 66°F | 53°F | 5.3" |
| May | 48°F | 77°F | 63°F | 4.3" |
| June | 61°F | 86°F | 73°F | 6.6" |
| July | 63°F | 86°F | 74°F | 5.1" |
| August | 65°F | 91°F | 77°F | 5.3" |
| September | 55°F | 85°F | 69°F | 3.7" |
| October | 46°F | 71°F | 57°F | 8.1" |
| November | 33°F | 57°F | 45°F | 6.9" |
| December | 25°F | 42°F | 33°F | 4.7" |
| Index | Landen | Ohio | National |
| Air quality index | 54 | 40 | 42 |
| Pollution index | 7,300,490 | 4,472,386 | 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 | 0.520% |
| Benzene | 0.070% |
| Carbon Tetrachloride | 0.040% |
| Lead | 0.240% |
| Mercury | 0.050% |
| City | Population | Air Quality Index | National Avg. |
| Lebanon, OH | 20,781 | 43 | 14.0% |
| Pleasant Plain, OH | 197 | 43 | 14.0% |
| Corwin, OH | 434 | 43 | 14.0% |
| Morrow, OH | 1,999 | 43 | 14.0% |
| Waynesville, OH | 3,135 | 43 | 14.0% |
| Landen, OH | 7,882 | 54 | 8.0% |
| City | Population | Air Quality Index | National Avg. |
| Grand Blanc, MI | 7,881 | 38 | 24.0% |
| Baltimore Highlands, MD | 7,880 | 46 | 8.0% |
| Ruidoso, NM | 7,879 | 10 | 80.0% |
| Camp Pendleton North, CA | 7,885 | 64 | 28.0% |
| Middletown, KY | 7,885 | 49 | 2.0% |
| Landen, OH | 7,882 | 54 | 8.0% |
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