| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 20°F | 35°F | 27°F | 2.3" |
| February | 20°F | 37°F | 28°F | 2.3" |
| March | 31°F | 51°F | 40°F | 3.2" |
| April | 41°F | 64°F | 52°F | 4.1" |
| May | 51°F | 74°F | 63°F | 4.3" |
| June | 61°F | 82°F | 71°F | 4.8" |
| July | 63°F | 85°F | 74°F | 3.5" |
| August | 61°F | 83°F | 72°F | 3.9" |
| September | 54°F | 78°F | 65°F | 2.7" |
| October | 44°F | 66°F | 54°F | 2.9" |
| November | 34°F | 53°F | 43°F | 2.7" |
| December | 26°F | 40°F | 33°F | 3.1" |
| Index | Delphos | Ohio | National |
| Air quality index | 39 | 40 | 42 |
| Pollution index | 850,677 | 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 | 0.002% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.010% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Cloverdale, OH | 167 | 39 | 22.0% |
| Columbus Grove, OH | 1,743 | 39 | 22.0% |
| Kalida, OH | 1,679 | 39 | 22.0% |
| Fort Shawnee, OH | 5,835 | 39 | 22.0% |
| Elida, OH | 1,995 | 39 | 22.0% |
| Delphos, OH | 7,066 | 39 | 22.0% |
| City | Population | Air Quality Index | National Avg. |
| Cos Cob, CT | 7,065 | 43 | 14.0% |
| Hudson Falls, NY | 7,067 | 35 | 30.0% |
| Saint-Apollinaire, QC | 7,067 | n/a | |
| Hewlett, NY | 7,064 | 51 | 2.0% |
| Orland Hills, IL | 7,069 | 55 | 10.0% |
| Delphos, OH | 7,066 | 39 | 22.0% |
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