| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 17°F | 34°F | 24°F | 3.4" |
| February | 18°F | 36°F | 26°F | 3.6" |
| March | 32°F | 52°F | 41°F | 3.5" |
| April | 41°F | 65°F | 52°F | 6.9" |
| May | 52°F | 74°F | 63°F | 7.1" |
| June | 62°F | 83°F | 72°F | 7.9" |
| July | 65°F | 86°F | 75°F | 8.4" |
| August | 63°F | 84°F | 73°F | 7.4" |
| September | 54°F | 78°F | 65°F | 8.9" |
| October | 44°F | 66°F | 54°F | 5.8" |
| November | 32°F | 52°F | 41°F | 4.0" |
| December | 22°F | 37°F | 29°F | 4.5" |
| Index | Gilson | Illinois | National |
| Air quality index | 41 | 41 | 42 |
| Pollution index | 1,709,230 | 3,148,694 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 285 |
| Days with moderate air quality | 78 |
| Days w/ poor A.Q. for sensitive groups | 2 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.050% |
| Carbon Tetrachloride | 0.040% |
| Lead | 0.001% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Knoxville, IL | 3,137 | 41 | 18.0% |
| Elmwood, IL | 2,492 | 41 | 18.0% |
| Abingdon, IL | 3,570 | 41 | 18.0% |
| Avon, IL | 690 | 41 | 18.0% |
| East Galesburg, IL | 579 | 41 | 18.0% |
| Gilson, IL | 194 | 41 | 18.0% |
| City | Population | Air Quality Index | National Avg. |
| Laurel, IA | 194 | 37 | 26.0% |
| Bison, KS | 194 | 15 | 70.0% |
| Maple Grove, MI | 194 | 36 | 28.0% |
| Bolckow, MO | 194 | 43 | 14.0% |
| Glen Acres, NM | 194 | 37 | 26.0% |
| Gilson, IL | 194 | 41 | 18.0% |
Here are the best places to live in Illinois
Check out the 10 safest cities in Illinois
See the best places to live in Gilson
These are the largest cities in Illinois