| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 27°F | 45°F | 35°F | 3.7" |
| February | 29°F | 47°F | 37°F | 3.9" |
| March | 39°F | 61°F | 49°F | 5.6" |
| April | 47°F | 70°F | 58°F | 5.4" |
| May | 57°F | 78°F | 67°F | 6.0" |
| June | 67°F | 89°F | 77°F | 2.9" |
| July | 68°F | 89°F | 78°F | 4.2" |
| August | 67°F | 90°F | 78°F | 3.2" |
| September | 59°F | 82°F | 70°F | 3.9" |
| October | 46°F | 70°F | 57°F | 6.3" |
| November | 38°F | 59°F | 48°F | 3.0" |
| December | 29°F | 46°F | 37°F | 5.5" |
| Index | Kelso | Missouri | National |
| Air quality index | 44 | 97 | 42 |
| Pollution index | 2,522,770 | 1,630,255 | 2,726,193 |
| Measurement | Total |
| Days measured | 364 |
| Days with good air quality | 261 |
| Days with moderate air quality | 103 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.060% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.030% |
| Mercury | 0.040% |
| City | Population | Air Quality Index | National Avg. |
| McClure, IL | 241 | 44 | 12.0% |
| Haywood City, MO | 103 | 44 | 12.0% |
| Allenville, MO | 101 | 44 | 12.0% |
| Dutchtown, MO | 110 | 44 | 12.0% |
| Whitewater, MO | 81 | 44 | 12.0% |
| Kelso, MO | 575 | 44 | 12.0% |
| City | Population | Air Quality Index | National Avg. |
| Tolani Lake, AZ | 575 | 45 | 10.0% |
| Newton, GA | 575 | 40 | 20.0% |
| Minnesota Lake, MN | 575 | 15 | 70.0% |
| Irondale, MO | 575 | 54 | 8.0% |
| Wibaux, MT | 575 | 33 | 34.0% |
| Kelso, MO | 575 | 44 | 12.0% |
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