| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 20°F | 36°F | 28°F | 2.4" |
| February | 21°F | 38°F | 29°F | 2.3" |
| March | 33°F | 52°F | 42°F | 4.0" |
| April | 42°F | 65°F | 53°F | 4.6" |
| May | 53°F | 75°F | 64°F | 4.6" |
| June | 62°F | 83°F | 72°F | 5.5" |
| July | 64°F | 85°F | 74°F | 3.2" |
| August | 61°F | 83°F | 72°F | 3.8" |
| September | 55°F | 78°F | 66°F | 3.0" |
| October | 44°F | 66°F | 55°F | 3.4" |
| November | 34°F | 53°F | 43°F | 3.4" |
| December | 26°F | 41°F | 33°F | 3.6" |
| Index | Middletown | Indiana | National |
| Air quality index | 42 | 56 | 42 |
| Pollution index | 1,974,040 | 2,719,453 | 2,726,193 |
| Measurement | Total |
| Days measured | 363 |
| Days with good air quality | 237 |
| Days with moderate air quality | 125 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality |
| Pollutant | Total |
| Arsenic | 0.002% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.002% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Mount Summit, IN | 408 | 28 | 44.0% |
| Wilkinson, IN | 439 | 28 | 44.0% |
| Cadiz, IN | 242 | 28 | 44.0% |
| Kennard, IN | 663 | 28 | 44.0% |
| New Castle, IN | 17,234 | 28 | 44.0% |
| Middletown, IN | 2,472 | 42 | 16.0% |
| City | Population | Air Quality Index | National Avg. |
| Keokea, HI | 2,471 | 15 | 70.0% |
| Merriam Woods, MO | 2,471 | 18 | 64.0% |
| Solomons, MD | 2,470 | 41 | 18.0% |
| Carthage, IL | 2,474 | 29 | 42.0% |
| St. Hedwig, TX | 2,474 | 49 | 2.0% |
| Middletown, IN | 2,472 | 42 | 16.0% |
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