| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 22°F | 35°F | 29°F | 7.9" |
| February | 18°F | 32°F | 25°F | 3.3" |
| March | 33°F | 51°F | 42°F | 4.8" |
| April | 42°F | 63°F | 53°F | 4.5" |
| May | 54°F | 75°F | 67°F | 4.0" |
| June | 65°F | 83°F | 75°F | 7.3" |
| July | 65°F | 83°F | 76°F | 6.5" |
| August | 66°F | 84°F | 77°F | 8.2" |
| September | 59°F | 81°F | 71°F | 11.9" |
| October | 49°F | 67°F | 59°F | 4.4" |
| November | 35°F | 51°F | 43°F | 7.4" |
| December | 23°F | 34°F | 29°F | 4.1" |
| Index | Mexico | Indiana | National |
| Air quality index | 37 | 56 | 42 |
| Pollution index | 2,150,900 | 2,719,453 | 2,726,193 |
| Measurement | Total |
| Days measured | 351 |
| Days with good air quality | 319 |
| Days with moderate air quality | 32 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.004% |
| Lead | 0.650% |
| Mercury | 1.040% |
| City | Population | Air Quality Index | National Avg. |
| Grissom AFB, IN | 2,368 | 37 | 26.0% |
| Roann, IN | 340 | 37 | 26.0% |
| Denver, IN | 597 | 37 | 26.0% |
| Onward, IN | 171 | 37 | 26.0% |
| Somerset, IN | 380 | 37 | 26.0% |
| Mexico, IN | 1,283 | 37 | 26.0% |
| City | Population | Air Quality Index | National Avg. |
| Clinton, OH | 1,283 | 43 | 14.0% |
| Gnadenhutten, OH | 1,283 | 46 | 8.0% |
| Brightwood, VA | 1,283 | 40 | 20.0% |
| Ignace, ON | 1,283 | n/a | |
| Woodstock, AL | 1,282 | 35 | 30.0% |
| Mexico, IN | 1,283 | 37 | 26.0% |
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