| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 19°F | 43°F | 30°F | 0.8" |
| February | 21°F | 46°F | 33°F | 1.6" |
| March | 34°F | 60°F | 46°F | 2.8" |
| April | 44°F | 69°F | 56°F | 4.4" |
| May | 53°F | 77°F | 65°F | 5.4" |
| June | 64°F | 87°F | 75°F | 5.6" |
| July | 68°F | 90°F | 79°F | 4.9" |
| August | 66°F | 89°F | 77°F | 5.7" |
| September | 57°F | 82°F | 69°F | 4.8" |
| October | 45°F | 71°F | 57°F | 3.9" |
| November | 34°F | 59°F | 46°F | 2.0" |
| December | 22°F | 44°F | 32°F | 1.8" |
| Index | Smithville | Missouri | National |
| Air quality index | 47 | 97 | 42 |
| Pollution index | 2,380,670 | 1,630,255 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 210 |
| Days with moderate air quality | 154 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.400% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.100% |
| Mercury | 0.230% |
| City | Population | Air Quality Index | National Avg. |
| Dearborn, MO | 551 | 43 | 14.0% |
| Trimble, MO | 545 | 43 | 14.0% |
| Edgerton, MO | 648 | 43 | 14.0% |
| Gower, MO | 1,661 | 43 | 14.0% |
| Lathrop, MO | 2,218 | 43 | 14.0% |
| Smithville, MO | 10,269 | 47 | 6.0% |
| City | Population | Air Quality Index | National Avg. |
| Mapleton, UT | 10,270 | 46 | 8.0% |
| Arden Hills, MN | 10,276 | 46 | 8.0% |
| Vienna, WV | 10,261 | 35 | 30.0% |
| Troy, IL | 10,278 | 54 | 8.0% |
| Milton, FL | 10,259 | 41 | 18.0% |
| Smithville, MO | 10,269 | 47 | 6.0% |
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