| 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 | Oconee | Illinois | National |
| Air quality index | 40 | 41 | 42 |
| Pollution index | 1,561,310 | 3,148,694 | 2,726,193 |
| Measurement | Total |
| Days measured | 245 |
| Days with good air quality | 224 |
| Days with moderate air quality | 21 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.040% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.002% |
| Mercury | 0.002% |
| City | Population | Air Quality Index | National Avg. |
| Herrick, IL | 367 | 40 | 20.0% |
| Coalton, IL | 337 | 40 | 20.0% |
| Fillmore, IL | 296 | 40 | 20.0% |
| Ramsey, IL | 871 | 40 | 20.0% |
| Witt, IL | 613 | 40 | 20.0% |
| Oconee, IL | 137 | 40 | 20.0% |
| City | Population | Air Quality Index | National Avg. |
| Pine Apple, AL | 137 | 52 | 4.0% |
| Waterloo, AL | 137 | 37 | 26.0% |
| Washington, CA | 137 | 44 | 12.0% |
| Pitkin, CO | 137 | 16 | 68.0% |
| Knoxville, GA | 137 | 38 | 24.0% |
| Oconee, IL | 137 | 40 | 20.0% |
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