| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 27°F | 44°F | 34°F | 11.5" |
| February | 27°F | 48°F | 36°F | 4.3" |
| March | 37°F | 62°F | 48°F | 2.8" |
| April | 45°F | 68°F | 55°F | 12.1" |
| May | 55°F | 80°F | 66°F | 4.6" |
| June | 64°F | 87°F | 74°F | 20.3" |
| July | 66°F | 91°F | 78°F | 2.7" |
| August | 70°F | 93°F | 80°F | 21.2" |
| September | 61°F | 84°F | 71°F | 6.9" |
| October | 49°F | 72°F | 58°F | 3.8" |
| November | 37°F | 61°F | 47°F | 3.2" |
| December | 27°F | 44°F | 34°F | 3.3" |
| Index | Olean | Missouri | National |
| Air quality index | 39 | 97 | 42 |
| Pollution index | 803,186 | 1,630,255 | 2,726,193 |
| Measurement | Total |
| Days measured | 245 |
| Days with good air quality | 238 |
| Days with moderate air quality | 7 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.010% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Tuscumbia, MO | 162 | 39 | 22.0% |
| Barnett, MO | 226 | 39 | 22.0% |
| Lohman, MO | 210 | 39 | 22.0% |
| Lake Ozark, MO | 2,317 | 39 | 22.0% |
| Eldon, MO | 4,671 | 39 | 22.0% |
| Olean, MO | 68 | 39 | 22.0% |
| City | Population | Air Quality Index | National Avg. |
| Ekwok, AK | 68 | 31 | 38.0% |
| Union Grove, AL | 68 | 44 | 12.0% |
| Anthonyville, AR | 68 | 45 | 10.0% |
| Marie, AR | 68 | 45 | 10.0% |
| Keddie, CA | 68 | 46 | 8.0% |
| Olean, MO | 68 | 39 | 22.0% |
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