| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 18°F | 35°F | 26°F | 5.9" |
| February | 21°F | 40°F | 30°F | 2.5" |
| March | 33°F | 54°F | 42°F | 5.0" |
| April | 42°F | 66°F | 53°F | 8.5" |
| May | 53°F | 76°F | 64°F | 7.3" |
| June | 62°F | 83°F | 72°F | 10.2" |
| July | 63°F | 85°F | 74°F | 6.2" |
| August | 60°F | 83°F | 71°F | 6.0" |
| September | 54°F | 78°F | 65°F | 9.2" |
| October | 43°F | 66°F | 53°F | 4.4" |
| November | 33°F | 53°F | 42°F | 6.4" |
| December | 25°F | 40°F | 32°F | 4.8" |
| Index | Thorntown | Indiana | National |
| Air quality index | 42 | 56 | 42 |
| Pollution index | 680,492 | 2,719,453 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 276 |
| Days with moderate air quality | 89 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Frankfort, IN | 15,569 | 42 | 16.0% |
| Ladoga, IN | 1,274 | 42 | 16.0% |
| New Ross, IN | 516 | 42 | 16.0% |
| Kirklin, IN | 1,125 | 42 | 16.0% |
| Mulberry, IN | 1,319 | 42 | 16.0% |
| Thorntown, IN | 1,077 | 42 | 16.0% |
| City | Population | Air Quality Index | National Avg. |
| Wenona, IL | 1,077 | 0 | 100.0% |
| Victoria, KS | 1,077 | 15 | 70.0% |
| Camargo, KY | 1,077 | 33 | 34.0% |
| Riverdale, VA | 1,077 | 44 | 12.0% |
| Jericho, VT | 1,077 | 37 | 26.0% |
| Thorntown, IN | 1,077 | 42 | 16.0% |
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