| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 22°F | 39°F | 30°F | 2.9" |
| February | 22°F | 40°F | 31°F | 2.3" |
| March | 34°F | 55°F | 44°F | 3.8" |
| April | 44°F | 68°F | 55°F | 5.1" |
| May | 54°F | 77°F | 65°F | 4.6" |
| June | 63°F | 85°F | 73°F | 6.3" |
| July | 64°F | 86°F | 75°F | 4.4" |
| August | 62°F | 85°F | 73°F | 3.0" |
| September | 56°F | 80°F | 67°F | 3.6" |
| October | 45°F | 68°F | 56°F | 3.5" |
| November | 34°F | 55°F | 44°F | 3.5" |
| December | 27°F | 43°F | 34°F | 4.1" |
| Index | Hartsville | Indiana | National |
| Air quality index | 41 | 56 | 42 |
| Pollution index | 847,937 | 2,719,453 | 2,726,193 |
| Measurement | Total |
| Days measured | 364 |
| Days with good air quality | 298 |
| Days with moderate air quality | 66 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.002% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Scipio, IN | 308 | 35 | 30.0% |
| Jonesville, IN | 223 | 35 | 30.0% |
| Waldron, IN | 648 | 41 | 18.0% |
| Hope, IN | 1,919 | 41 | 18.0% |
| Columbus, IN | 48,820 | 41 | 18.0% |
| Hartsville, IN | 416 | 41 | 18.0% |
| City | Population | Air Quality Index | National Avg. |
| Jerome, AZ | 416 | 43 | 14.0% |
| St. Mary's, CO | 416 | 47 | 6.0% |
| Between, GA | 416 | 44 | 12.0% |
| Earling, IA | 416 | 40 | 20.0% |
| Hazleton, IN | 416 | 36 | 28.0% |
| Hartsville, IN | 416 | 41 | 18.0% |
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