| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 22°F | 37°F | 29°F | 8.1" |
| February | 18°F | 34°F | 26°F | 4.1" |
| March | 32°F | 52°F | 41°F | 5.7" |
| April | 40°F | 64°F | 51°F | 7.1" |
| May | 51°F | 75°F | 63°F | 2.9" |
| June | 62°F | 84°F | 73°F | 4.0" |
| July | 61°F | 84°F | 72°F | 4.9" |
| August | 64°F | 85°F | 74°F | 8.8" |
| September | 57°F | 81°F | 68°F | 4.3" |
| October | 49°F | 68°F | 58°F | 5.4" |
| November | 34°F | 53°F | 43°F | 6.2" |
| December | 22°F | 36°F | 29°F | 5.0" |
| Index | Union City | Indiana | National |
| Air quality index | 6 | 56 | 42 |
| Pollution index | 1,533,570 | 2,719,453 | 2,726,193 |
| Measurement | Total |
| Days measured | 364 |
| Days with good air quality | 364 |
| Days with moderate air quality | |
| Days w/ poor A.Q. for sensitive groups | |
| Days with unhealthy air quality |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.003% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Hollansburg, OH | 273 | 6 | 88.0% |
| Burkettsville, OH | 249 | 6 | 88.0% |
| Greenville, OH | 12,743 | 6 | 88.0% |
| Ansonia, OH | 1,126 | 6 | 88.0% |
| Wayne Lakes, OH | 834 | 6 | 88.0% |
| Union City, IN | 3,385 | 6 | 88.0% |
| City | Population | Air Quality Index | National Avg. |
| Carey, OH | 3,386 | 39 | 22.0% |
| Marathon, ON | 3,386 | n/a | |
| Jewett City, CT | 3,387 | 37 | 26.0% |
| Blountville, TN | 3,387 | 45 | 10.0% |
| Wolf Lake, MI | 3,382 | 36 | 28.0% |
| Union City, IN | 3,385 | 6 | 88.0% |
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