| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 24°F | 45°F | 33°F | 2.4" |
| February | 25°F | 48°F | 35°F | 2.2" |
| March | 37°F | 61°F | 48°F | 3.6" |
| April | 47°F | 72°F | 59°F | 5.4" |
| May | 57°F | 80°F | 68°F | 4.6" |
| June | 67°F | 89°F | 78°F | 5.2" |
| July | 70°F | 92°F | 81°F | 4.2" |
| August | 69°F | 91°F | 79°F | 3.6" |
| September | 61°F | 84°F | 72°F | 4.3" |
| October | 48°F | 72°F | 60°F | 3.4" |
| November | 37°F | 60°F | 48°F | 3.4" |
| December | 27°F | 47°F | 37°F | 3.5" |
| Index | Dellwood | Missouri | National |
| Air quality index | 54 | 97 | 42 |
| Pollution index | 8,473,050 | 1,630,255 | 2,726,193 |
| 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. |
| Velda Village Hills, MO | 869 | 54 | 8.0% |
| Berkeley, MO | 8,912 | 54 | 8.0% |
| Champ, MO | 3 | 54 | 8.0% |
| Hazelwood, MO | 25,222 | 54 | 8.0% |
| St. Ann, MO | 12,689 | 54 | 8.0% |
| Dellwood, MO | 5,010 | 54 | 8.0% |
| City | Population | Air Quality Index | National Avg. |
| Veneta, OR | 5,010 | 38 | 24.0% |
| West Salem, WI | 5,010 | 35 | 30.0% |
| Lawrenceburg, IN | 5,009 | 54 | 8.0% |
| Manchester, IA | 5,011 | 39 | 22.0% |
| Abbeville, SC | 5,014 | 31 | 38.0% |
| Dellwood, MO | 5,010 | 54 | 8.0% |
Here are the best places to live in Missouri
See the best places to live in Dellwood
These are the 10 cheapest cities in Missouri
These are the largest cities in Missouri