| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 19°F | 35°F | 27°F | 3.2" |
| February | 20°F | 38°F | 28°F | 2.3" |
| March | 34°F | 53°F | 42°F | 3.3" |
| April | 44°F | 67°F | 54°F | 5.2" |
| May | 54°F | 77°F | 65°F | 5.3" |
| June | 64°F | 85°F | 74°F | 6.5" |
| July | 66°F | 86°F | 76°F | 5.8" |
| August | 65°F | 85°F | 74°F | 9.3" |
| September | 58°F | 80°F | 68°F | 8.3" |
| October | 46°F | 68°F | 56°F | 4.7" |
| November | 35°F | 54°F | 43°F | 4.6" |
| December | 25°F | 40°F | 32°F | 3.9" |
| Index | Sibley | Illinois | National |
| Air quality index | 44 | 41 | 42 |
| Pollution index | 7,745,200 | 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 | 0.030% |
| Benzene | 0.070% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.860% |
| Mercury | 0.210% |
| City | Population | Air Quality Index | National Avg. |
| Paxton, IL | 4,076 | 42 | 16.0% |
| Roberts, IL | 470 | 42 | 16.0% |
| Piper City, IL | 855 | 42 | 16.0% |
| Elliott, IL | 310 | 42 | 16.0% |
| Gibson City, IL | 3,340 | 42 | 16.0% |
| Sibley, IL | 223 | 44 | 12.0% |
| City | Population | Air Quality Index | National Avg. |
| Tillar, AR | 223 | 43 | 14.0% |
| Avera, GA | 223 | 47 | 6.0% |
| Alta Vista, IA | 223 | 15 | 70.0% |
| Ladora, IA | 223 | 39 | 22.0% |
| Acequia, ID | 223 | 20 | 60.0% |
| Sibley, IL | 223 | 44 | 12.0% |
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