| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 19°F | 35°F | 27°F | 2.2" |
| February | 19°F | 37°F | 27°F | 2.0" |
| March | 30°F | 50°F | 39°F | 3.1" |
| April | 40°F | 64°F | 51°F | 3.5" |
| May | 51°F | 74°F | 62°F | 4.2" |
| June | 60°F | 82°F | 70°F | 5.2" |
| July | 62°F | 84°F | 73°F | 4.0" |
| August | 60°F | 83°F | 71°F | 3.4" |
| September | 53°F | 77°F | 64°F | 3.4" |
| October | 43°F | 65°F | 53°F | 3.4" |
| November | 32°F | 52°F | 42°F | 2.6" |
| December | 25°F | 41°F | 32°F | 3.0" |
| Index | Marseilles | Ohio | National |
| Air quality index | 39 | 40 | 42 |
| Pollution index | 750,178 | 4,472,386 | 2,726,193 |
| Measurement | Total |
| Days measured | 364 |
| Days with good air quality | 303 |
| Days with moderate air quality | 61 |
| 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 | 0.002% |
| Lead | 0.002% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Mount Victory, OH | 680 | 39 | 22.0% |
| Kenton, OH | 8,615 | 39 | 22.0% |
| Kirby, OH | 107 | 39 | 22.0% |
| Wharton, OH | 426 | 39 | 22.0% |
| Ridgeway, OH | 358 | 39 | 22.0% |
| Marseilles, OH | 85 | 39 | 22.0% |
| City | Population | Air Quality Index | National Avg. |
| Pilot Point, AK | 85 | 31 | 38.0% |
| Higden, AR | 85 | 45 | 10.0% |
| Nimmons, AR | 85 | 26 | 48.0% |
| Kirk, CO | 85 | 58 | 16.0% |
| Ledyard, IA | 85 | 15 | 70.0% |
| Marseilles, OH | 85 | 39 | 22.0% |