| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 21°F | 39°F | 28°F | 4.0" |
| February | 24°F | 44°F | 31°F | 4.7" |
| March | 36°F | 59°F | 46°F | 8.0" |
| April | 43°F | 66°F | 54°F | 4.6" |
| May | 55°F | 78°F | 65°F | 4.8" |
| June | 64°F | 85°F | 74°F | 11.0" |
| July | 66°F | 89°F | 77°F | 3.6" |
| August | 68°F | 91°F | 78°F | 9.7" |
| September | 58°F | 84°F | 69°F | 5.8" |
| October | 48°F | 69°F | 57°F | 8.3" |
| November | 33°F | 57°F | 44°F | 2.5" |
| December | 21°F | 37°F | 28°F | 4.6" |
| Index | Sumner | Missouri | National |
| Air quality index | 38 | 97 | 42 |
| Pollution index | 527,976 | 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 | 0.002% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.003% |
| Mercury | 0.002% |
| City | Population | Air Quality Index | National Avg. |
| Brookfield, MO | 4,265 | 38 | 24.0% |
| Hale, MO | 445 | 38 | 24.0% |
| Laclede, MO | 322 | 38 | 24.0% |
| Mendon, MO | 271 | 38 | 24.0% |
| Meadville, MO | 559 | 38 | 24.0% |
| Sumner, MO | 117 | 38 | 24.0% |
| City | Population | Air Quality Index | National Avg. |
| Primrose, AK | 117 | 31 | 38.0% |
| Bryce, AZ | 117 | 47 | 6.0% |
| Pine Lake, AZ | 117 | 13 | 74.0% |
| Milford, CA | 117 | 46 | 8.0% |
| Matlock, IA | 117 | 36 | 28.0% |
| Sumner, MO | 117 | 38 | 24.0% |
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