| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 18°F | 33°F | 25°F | 3.9" |
| February | 18°F | 35°F | 26°F | 2.3" |
| March | 31°F | 50°F | 39°F | 4.3" |
| April | 40°F | 63°F | 50°F | 8.4" |
| May | 51°F | 74°F | 62°F | 6.0" |
| June | 61°F | 82°F | 71°F | 5.7" |
| July | 63°F | 84°F | 73°F | 9.0" |
| August | 62°F | 82°F | 71°F | 5.4" |
| September | 54°F | 77°F | 65°F | 3.7" |
| October | 44°F | 65°F | 53°F | 7.1" |
| November | 33°F | 51°F | 41°F | 4.0" |
| December | 22°F | 37°F | 29°F | 3.0" |
| Index | Sheridan | Illinois | National |
| Air quality index | 0 | 41 | 50 |
| Pollution index | 1,874,490 | 3,347,295 | 5,066,862 |
| 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 | 0.002% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.010% |
| Mercury | 0.010% |
| City, State | Population | Air Quality Index | National Avg. |
| Earlville, IL | 1,672 | 0 | 100% |
| Millington, IL | 629 | 0 | 100% |
| Naplate, IL | 441 | 0 | 100% |
| Plano, IL | 11,929 | 0 | 100% |
| Lake Holiday, IL | 4,718 | 0 | 100% |
| Sheridan, IL | 2,543 | 0 | 100% |
| City, State | Population | Air Quality Index | National Avg. |
| Williamsburg, OH | 2,543 | 54 | 8% |
| Evansburg, PA | 2,543 | 51 | 2% |
| Imperial, PA | 2,543 | 56 | 12% |
| Calvert City, KY | 2,544 | 44 | 12% |
| Wayne Heights, PA | 2,545 | 40 | 20% |
| Sheridan, IL | 2,543 | 0 | 100% |
Here are the best places to live in Illinois
These are the 10 most affordable cities in Illinois
Top 10 cities in Illinois with the best education system
Check out the 10 safest cities in Illinois