| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 22°F | 37°F | 28°F | 2.4" |
| February | 23°F | 39°F | 30°F | 1.0" |
| March | 36°F | 55°F | 44°F | 4.5" |
| April | 45°F | 67°F | 55°F | 12.9" |
| May | 55°F | 76°F | 65°F | 9.0" |
| June | 64°F | 85°F | 73°F | 4.0" |
| July | 66°F | 87°F | 76°F | 15.2" |
| August | 64°F | 86°F | 74°F | 6.8" |
| September | 57°F | 80°F | 67°F | 6.1" |
| October | 46°F | 67°F | 55°F | 4.5" |
| November | 36°F | 54°F | 44°F | 3.5" |
| December | 27°F | 40°F | 33°F | 2.2" |
| Index | Owaneco | Illinois | National |
| Air quality index | 44 | 41 | 42 |
| Pollution index | 2,357,280 | 3,148,694 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 255 |
| Days with moderate air quality | 110 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.002% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.004% |
| Lead | 0.010% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Jeisyville, IL | 58 | 40 | 20.0% |
| Taylorville, IL | 10,766 | 40 | 20.0% |
| Nokomis, IL | 2,213 | 40 | 20.0% |
| Palmer, IL | 288 | 40 | 20.0% |
| Kincaid, IL | 1,428 | 40 | 20.0% |
| Owaneco, IL | 259 | 44 | 12.0% |
| City | Population | Air Quality Index | National Avg. |
| Chelsea, IA | 259 | 39 | 22.0% |
| Bovill, ID | 259 | 10 | 80.0% |
| Verona, IL | 259 | 0 | 100.0% |
| Prescott, MI | 259 | 26 | 48.0% |
| Alexander, ND | 259 | 34 | 32.0% |
| Owaneco, IL | 259 | 44 | 12.0% |
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