| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 24°F | 43°F | 32°F | 1.8" |
| February | 26°F | 45°F | 34°F | 1.6" |
| March | 37°F | 59°F | 47°F | 3.7" |
| April | 47°F | 70°F | 58°F | 5.3" |
| May | 56°F | 78°F | 67°F | 4.8" |
| June | 65°F | 88°F | 76°F | 4.4" |
| July | 68°F | 90°F | 79°F | 3.9" |
| August | 66°F | 89°F | 77°F | 3.1" |
| September | 58°F | 82°F | 69°F | 4.2" |
| October | 47°F | 71°F | 58°F | 3.1" |
| November | 36°F | 58°F | 46°F | 2.8" |
| December | 29°F | 45°F | 36°F | 3.1" |
| Index | Peabody-Darst-Webbe | St. Louis | Missouri |
| Air quality index | 54 | 54 | 97 |
| Pollution index | 8,473,050 | 8,473,050 | 1,630,255 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 134 |
| Days with moderate air quality | 221 |
| Days w/ poor A.Q. for sensitive groups | 8 |
| Days with unhealthy air quality | 2 |
| Pollutant | Total |
| Arsenic | 0.020% |
| Benzene | 0.070% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.010% |
| Mercury | 0.010% |
| City | Population | Air Quality Index | National Avg. |
| Florissant, MO | 51,220 | 54 | 8.0% |
| Maryville, IL | 7,962 | 54 | 8.0% |
| Bellefontaine Neighbors, MO | 10,441 | 54 | 8.0% |
| Millstadt, IL | 3,882 | 54 | 8.0% |
| Country Life Acres, MO | 52 | 54 | 8.0% |
| St. Louis, MO | 304,709 | 54 | 8.0% |
| City | Population | Air Quality Index | National Avg. |
| St. Paul, MN | 305,877 | 46 | 8.0% |
| Cincinnati, OH | 302,687 | 54 | 8.0% |
| Pittsburgh, PA | 301,286 | 56 | 12.0% |
| Henderson, NV | 309,955 | 54 | 8.0% |
| Stockton, CA | 311,103 | 45 | 10.0% |
| St. Louis, MO | 304,709 | 54 | 8.0% |
Here are the best places to live in Missouri
Check out the 10 safest cities in Missouri
These are the 10 most affordable cities in Missouri
10 best cities to buy a new house in Missouri