| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 18°F | 34°F | 25°F | 3.2" |
| February | 19°F | 36°F | 27°F | 3.2" |
| March | 32°F | 51°F | 41°F | 5.1" |
| April | 42°F | 64°F | 52°F | 6.5" |
| May | 53°F | 74°F | 63°F | 7.0" |
| June | 62°F | 82°F | 72°F | 7.0" |
| July | 65°F | 85°F | 74°F | 7.2" |
| August | 64°F | 84°F | 73°F | 8.3" |
| September | 57°F | 78°F | 66°F | 7.1" |
| October | 45°F | 65°F | 54°F | 6.0" |
| November | 34°F | 52°F | 42°F | 4.6" |
| December | 23°F | 38°F | 30°F | 3.8" |
| Index | Wenona | Illinois | National |
| Air quality index | 0 | 41 | 42 |
| Pollution index | 7,745,200 | 3,148,694 | 2,726,193 |
| Measurement | Total |
| Days measured | 335 |
| Days with good air quality | 334 |
| Days with moderate air quality | 1 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.030% |
| Benzene | 0.070% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.860% |
| Mercury | 0.210% |
| City | Population | Air Quality Index | National Avg. |
| Streator, IL | 12,337 | 0 | 100.0% |
| Rutland, IL | 279 | 0 | 100.0% |
| Mark, IL | 534 | 0 | 100.0% |
| Kangley, IL | 244 | 0 | 100.0% |
| Lostant, IL | 463 | 0 | 100.0% |
| Wenona, IL | 1,077 | 0 | 100.0% |
| City | Population | Air Quality Index | National Avg. |
| Thorntown, IN | 1,077 | 42 | 16.0% |
| 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% |
| Wenona, IL | 1,077 | 0 | 100.0% |
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