| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 22°F | 35°F | 28°F | 4.7" |
| February | 20°F | 34°F | 26°F | 2.5" |
| March | 33°F | 54°F | 42°F | 4.9" |
| April | 42°F | 65°F | 52°F | 4.6" |
| May | 53°F | 77°F | 65°F | 3.7" |
| June | 64°F | 86°F | 74°F | 4.4" |
| July | 65°F | 86°F | 75°F | 4.9" |
| August | 66°F | 88°F | 76°F | 3.8" |
| September | 59°F | 85°F | 70°F | 4.4" |
| October | 48°F | 70°F | 57°F | 5.3" |
| November | 34°F | 53°F | 42°F | 5.3" |
| December | 20°F | 33°F | 26°F | 2.9" |
| Index | Wapella | Illinois | National |
| Air quality index | 44 | 41 | 42 |
| Pollution index | 607,262 | 3,148,694 | 2,726,193 |
| Measurement | Total |
| Days measured | 364 |
| Days with good air quality | 256 |
| Days with moderate air quality | 108 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| McLean, IL | 808 | 44 | 12.0% |
| Le Roy, IL | 3,429 | 44 | 12.0% |
| Kenney, IL | 447 | 44 | 12.0% |
| De Witt, IL | 221 | 44 | 12.0% |
| Waynesville, IL | 496 | 44 | 12.0% |
| Wapella, IL | 474 | 44 | 12.0% |
| City | Population | Air Quality Index | National Avg. |
| McNeil, AR | 474 | 35 | 30.0% |
| Siloam, GA | 474 | 44 | 12.0% |
| Bentley, KS | 474 | 40 | 20.0% |
| Glasco, KS | 474 | 32 | 36.0% |
| Natchez, LA | 474 | 30 | 40.0% |
| Wapella, IL | 474 | 44 | 12.0% |
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