| 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 | 50 |
| Pollution index | 1,561,310 | 3,347,295 | 5,066,862 |
| 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, State | Population | Air Quality Index | National Avg. |
| Ohlman, IL | 113 | 40 | 20% |
| Tower Hill, IL | 599 | 40 | 20% |
| Cowden, IL | 534 | 40 | 20% |
| Wenonah, IL | 40 | 40 | 20% |
| Bingham, IL | 61 | 40 | 20% |
| Oconee, IL | 183 | 40 | 20% |
| City, State | Population | Air Quality Index | National Avg. |
| Garden Grove, IA | 183 | 39 | 22% |
| Canadian, OK | 183 | 43 | 14% |
| Rupert, PA | 183 | 35 | 30% |
| Sobieski, MN | 183 | 32 | 36% |
| Wyola, MT | 183 | 39 | 22% |
| Oconee, IL | 183 | 40 | 20% |
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