| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 24°F | 39°F | 31°F | 7.7" |
| February | 18°F | 35°F | 26°F | 2.3" |
| March | 29°F | 50°F | 39°F | 4.6" |
| April | 37°F | 62°F | 49°F | 7.9" |
| May | 45°F | 73°F | 59°F | 4.7" |
| June | 57°F | 83°F | 70°F | 2.9" |
| July | 61°F | 84°F | 72°F | 6.2" |
| August | 63°F | 84°F | 73°F | 7.9" |
| September | 53°F | 80°F | 65°F | 3.3" |
| October | 46°F | 68°F | 56°F | 4.1" |
| November | 33°F | 55°F | 44°F | 4.0" |
| December | 25°F | 40°F | 32°F | 4.1" |
| Index | Barnhill | Ohio | National |
| Air quality index | 46 | 40 | 42 |
| Pollution index | 724,968 | 4,472,386 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 226 |
| Days with moderate air quality | 139 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.030% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Deersville, OH | 12 | 39 | 22.0% |
| Tippecanoe, OH | 97 | 39 | 22.0% |
| Roswell, OH | 196 | 46 | 8.0% |
| Dundee, OH | 654 | 46 | 8.0% |
| Dellroy, OH | 256 | 46 | 8.0% |
| Barnhill, OH | 622 | 46 | 8.0% |
| City | Population | Air Quality Index | National Avg. |
| Cedarville, IL | 622 | 42 | 16.0% |
| Thayer, IL | 622 | 40 | 20.0% |
| Cloverdale, MS | 622 | 30 | 40.0% |
| Furman, SC | 622 | 29 | 42.0% |
| Wattsville, VA | 622 | 36 | 28.0% |
| Barnhill, OH | 622 | 46 | 8.0% |
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