| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 23°F | 44°F | 32°F | 1.0" |
| February | 26°F | 46°F | 34°F | 1.3" |
| March | 38°F | 60°F | 48°F | 2.5" |
| April | 47°F | 70°F | 57°F | 4.4" |
| May | 57°F | 77°F | 66°F | 4.2" |
| June | 67°F | 87°F | 76°F | 4.7" |
| July | 70°F | 90°F | 79°F | 3.6" |
| August | 67°F | 89°F | 77°F | 2.3" |
| September | 59°F | 81°F | 69°F | 3.7" |
| October | 48°F | 70°F | 58°F | 3.7" |
| November | 38°F | 58°F | 47°F | 2.4" |
| December | 28°F | 45°F | 35°F | 1.8" |
| Index | Ionia | Missouri | National |
| Air quality index | 38 | 97 | 42 |
| Pollution index | 1,664,220 | 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 | 0.090% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.020% |
| Mercury | 0.040% |
| City | Population | Air Quality Index | National Avg. |
| Green Ridge, MO | 473 | 38 | 24.0% |
| Sedalia, MO | 21,634 | 38 | 24.0% |
| Smithton, MO | 511 | 38 | 24.0% |
| Tightwad, MO | 80 | 39 | 22.0% |
| Lincoln, MO | 1,210 | 39 | 22.0% |
| Ionia, MO | 75 | 38 | 24.0% |
| City | Population | Air Quality Index | National Avg. |
| False Pass, AK | 75 | 31 | 38.0% |
| Lowndesboro, AL | 75 | 52 | 4.0% |
| Omaha, AR | 75 | 18 | 64.0% |
| Franklin, AZ | 75 | 37 | 26.0% |
| Gold Mountain, CA | 75 | 44 | 12.0% |
| Ionia, MO | 75 | 38 | 24.0% |
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