| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 25°F | 41°F | 32°F | 5.0" |
| February | 26°F | 43°F | 34°F | 3.4" |
| March | 38°F | 58°F | 47°F | 4.9" |
| April | 47°F | 69°F | 57°F | 9.7" |
| May | 57°F | 77°F | 66°F | 7.4" |
| June | 66°F | 87°F | 76°F | 8.6" |
| July | 68°F | 89°F | 78°F | 6.6" |
| August | 66°F | 88°F | 76°F | 8.7" |
| September | 58°F | 81°F | 68°F | 7.6" |
| October | 47°F | 70°F | 58°F | 7.1" |
| November | 37°F | 57°F | 46°F | 6.0" |
| December | 30°F | 45°F | 36°F | 6.6" |
| Index | Centralia | Illinois | National |
| Air quality index | 43 | 41 | 42 |
| Pollution index | 647,280 | 3,148,694 | 2,726,193 |
| Measurement | Total |
| Days measured | 344 |
| Days with good air quality | 269 |
| Days with moderate air quality | 74 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Ashley, IL | 471 | 43 | 14.0% |
| Mount Vernon, IL | 14,769 | 43 | 14.0% |
| Odin, IL | 999 | 43 | 14.0% |
| Hoffman, IL | 775 | 43 | 14.0% |
| Wamac, IL | 1,222 | 43 | 14.0% |
| Centralia, IL | 12,354 | 43 | 14.0% |
| City | Population | Air Quality Index | National Avg. |
| Wellesley, ON | 12,358 | n/a | |
| Grenada, MS | 12,349 | 33 | 34.0% |
| Winnetka, IL | 12,361 | 55 | 10.0% |
| Lakeland Village, CA | 12,362 | 89 | 78.0% |
| Urbana, MD | 12,362 | 40 | 20.0% |
| Centralia, IL | 12,354 | 43 | 14.0% |
Here are the best places to live in Illinois
See the best places to live in Centralia
Safest States In The US
Check out the 10 most dangerous cities in Illinois