| 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 | Langleyville | Illinois | National |
| Air quality index | 40 | 41 | 42 |
| Pollution index | 5,136,080 | 3,148,694 | 2,726,193 |
| Measurement | Total |
| Days measured | 360 |
| Days with good air quality | 287 |
| Days with moderate air quality | 73 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.090% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.390% |
| Mercury | 0.020% |
| City | Population | Air Quality Index | National Avg. |
| Palmer, IL | 288 | 40 | 20.0% |
| Kincaid, IL | 1,428 | 40 | 20.0% |
| Morrisonville, IL | 1,123 | 40 | 20.0% |
| Bulpitt, IL | 236 | 40 | 20.0% |
| Pawnee, IL | 2,522 | 40 | 20.0% |
| Langleyville, IL | 439 | 40 | 20.0% |
| City | Population | Air Quality Index | National Avg. |
| Epes, AL | 439 | 36 | 28.0% |
| Scotland, GA | 439 | 26 | 48.0% |
| Farnhamville, IA | 439 | 37 | 26.0% |
| Wilkinson, IN | 439 | 28 | 44.0% |
| Claflin, KS | 439 | 40 | 20.0% |
| Langleyville, IL | 439 | 40 | 20.0% |
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