| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 25°F | 47°F | 35°F | 2.3" |
| February | 27°F | 49°F | 37°F | 2.6" |
| March | 38°F | 61°F | 49°F | 4.9" |
| April | 47°F | 71°F | 58°F | 6.0" |
| May | 55°F | 77°F | 65°F | 5.7" |
| June | 65°F | 86°F | 75°F | 3.7" |
| July | 68°F | 89°F | 78°F | 4.7" |
| August | 66°F | 88°F | 76°F | 4.0" |
| September | 58°F | 81°F | 69°F | 3.5" |
| October | 47°F | 70°F | 58°F | 4.0" |
| November | 37°F | 59°F | 47°F | 3.4" |
| December | 29°F | 48°F | 38°F | 3.5" |
| Index | Thayer | Missouri | National |
| Air quality index | 36 | 97 | 42 |
| Pollution index | 305,376 | 1,630,255 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 347 |
| Days with moderate air quality | 18 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Alton, MO | 638 | 36 | 28.0% |
| Brandsville, MO | 191 | 36 | 28.0% |
| Hardy, AR | 765 | 36 | 28.0% |
| Koshkonong, MO | 153 | 36 | 28.0% |
| Mammoth Spring, AR | 1,117 | 36 | 28.0% |
| Thayer, MO | 2,578 | 36 | 28.0% |
| City | Population | Air Quality Index | National Avg. |
| Independence, LA | 2,578 | 30 | 40.0% |
| Jefferson, MD | 2,577 | 40 | 20.0% |
| Maine, WI | 2,577 | 34 | 32.0% |
| Hébertville, QC | 2,577 | n/a | |
| Loogootee, IN | 2,579 | 1 | 98.0% |
| Thayer, MO | 2,578 | 36 | 28.0% |
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