| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 21°F | 44°F | 31°F | 2.0" |
| February | 23°F | 47°F | 33°F | 2.1" |
| March | 35°F | 61°F | 46°F | 3.0" |
| April | 44°F | 71°F | 57°F | 5.7" |
| May | 53°F | 78°F | 65°F | 4.3" |
| June | 63°F | 87°F | 75°F | 4.8" |
| July | 67°F | 90°F | 78°F | 5.1" |
| August | 65°F | 89°F | 76°F | 3.9" |
| September | 57°F | 82°F | 69°F | 4.8" |
| October | 45°F | 71°F | 57°F | 3.9" |
| November | 35°F | 59°F | 46°F | 2.4" |
| December | 25°F | 45°F | 34°F | 2.7" |
| Index | Centralia | Missouri | National |
| Air quality index | 38 | 97 | 42 |
| Pollution index | 711,791 | 1,630,255 | 2,726,193 |
| Measurement | Total |
| Days measured | 245 |
| Days with good air quality | 239 |
| Days with moderate air quality | 6 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.002% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.003% |
| Lead | 0.010% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Clark, MO | 262 | 38 | 24.0% |
| Mexico, MO | 11,861 | 38 | 24.0% |
| Renick, MO | 157 | 38 | 24.0% |
| Sturgeon, MO | 1,142 | 38 | 24.0% |
| Auxvasse, MO | 1,254 | 38 | 24.0% |
| Centralia, MO | 4,354 | 38 | 24.0% |
| City | Population | Air Quality Index | National Avg. |
| Pittsfield, IL | 4,354 | 41 | 18.0% |
| Forsyth, GA | 4,353 | 38 | 24.0% |
| Lafayette, OR | 4,353 | 32 | 36.0% |
| Thiells, NY | 4,355 | 36 | 28.0% |
| Northern Bruce Peninsula, ON | 4,355 | n/a | |
| Centralia, MO | 4,354 | 38 | 24.0% |