| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 25°F | 40°F | 31°F | 6.8" |
| February | 27°F | 44°F | 34°F | 4.4" |
| March | 39°F | 60°F | 48°F | 3.5" |
| April | 45°F | 66°F | 55°F | 5.5" |
| May | 58°F | 78°F | 67°F | 4.3" |
| June | 66°F | 85°F | 75°F | 13.6" |
| July | 68°F | 89°F | 78°F | 5.0" |
| August | 70°F | 91°F | 80°F | 12.7" |
| September | 62°F | 83°F | 72°F | 6.1" |
| October | 50°F | 70°F | 59°F | 4.9" |
| November | 38°F | 58°F | 47°F | 4.1" |
| December | 25°F | 40°F | 32°F | 2.7" |
| Index | Marshall | Missouri | National |
| Air quality index | 38 | 97 | 42 |
| Pollution index | 2,921,360 | 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 | 0.030% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.070% |
| Mercury | 0.003% |
| City | Population | Air Quality Index | National Avg. |
| Blackwater, MO | 217 | 38 | 24.0% |
| Gilliam, MO | 193 | 38 | 24.0% |
| Houstonia, MO | 256 | 38 | 24.0% |
| Mount Leonard, MO | 22 | 38 | 24.0% |
| Slater, MO | 2,163 | 38 | 24.0% |
| Marshall, MO | 13,323 | 38 | 24.0% |
| City | Population | Air Quality Index | National Avg. |
| Edgewater, NJ | 13,325 | 51 | 2.0% |
| Los Alamos, NM | 13,326 | 8 | 84.0% |
| Greenwich, CT | 13,319 | 43 | 14.0% |
| Coolidge, AZ | 13,315 | 74 | 48.0% |
| Grass Valley, CA | 13,311 | 44 | 12.0% |
| Marshall, MO | 13,323 | 38 | 24.0% |