| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 20°F | 35°F | 27°F | 3.3" |
| February | 19°F | 34°F | 26°F | 3.0" |
| March | 29°F | 47°F | 37°F | 3.5" |
| April | 40°F | 62°F | 51°F | 3.3" |
| May | 49°F | 70°F | 59°F | 3.9" |
| June | 59°F | 80°F | 69°F | 5.8" |
| July | 61°F | 82°F | 72°F | 4.1" |
| August | 61°F | 81°F | 71°F | 5.2" |
| September | 54°F | 75°F | 64°F | 3.8" |
| October | 43°F | 62°F | 52°F | 3.9" |
| November | 34°F | 51°F | 42°F | 2.7" |
| December | 24°F | 38°F | 30°F | 3.9" |
| Index | Plymouth | Ohio | National |
| Air quality index | 41 | 40 | 42 |
| Pollution index | 2,498,190 | 4,472,386 | 2,726,193 |
| Measurement | Total |
| Days measured | 245 |
| Days with good air quality | 218 |
| Days with moderate air quality | 27 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.004% |
| Lead | 0.003% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Greenwich, OH | 1,489 | 41 | 18.0% |
| Tiro, OH | 219 | 41 | 18.0% |
| Sulphur Springs, OH | 159 | 41 | 18.0% |
| Willard, OH | 6,028 | 41 | 18.0% |
| Chatfield, OH | 300 | 41 | 18.0% |
| Plymouth, OH | 1,607 | 41 | 18.0% |
| City | Population | Air Quality Index | National Avg. |
| Northville, NY | 1,607 | 41 | 18.0% |
| City View, SC | 1,607 | 46 | 8.0% |
| Florenceville-Bristol, NB | 1,607 | n/a | |
| Notre-Dame-du-Laus, QC | 1,607 | n/a | |
| Walpole Island 46, ON | 1,607 | n/a | |
| Plymouth, OH | 1,607 | 41 | 18.0% |
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