| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 29°F | 52°F | 39°F | 4.2" |
| February | 31°F | 54°F | 42°F | 3.4" |
| March | 39°F | 65°F | 52°F | 4.1" |
| April | 49°F | 75°F | 62°F | 5.6" |
| May | 56°F | 82°F | 69°F | 5.1" |
| June | 66°F | 90°F | 78°F | 3.9" |
| July | 69°F | 92°F | 80°F | 5.0" |
| August | 69°F | 92°F | 79°F | 4.5" |
| September | 61°F | 86°F | 73°F | 4.0" |
| October | 49°F | 75°F | 61°F | 4.0" |
| November | 38°F | 64°F | 50°F | 3.8" |
| December | 33°F | 54°F | 43°F | 5.1" |
| Index | Graball | Tennessee | National |
| Air quality index | 45 | 76 | 42 |
| Pollution index | 1,764,100 | 2,454,916 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 229 |
| Days with moderate air quality | 135 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.004% |
| Lead | 0.030% |
| Mercury | 0.010% |
| City | Population | Air Quality Index | National Avg. |
| Westmoreland, TN | 2,622 | 43 | 14.0% |
| Fairfield, TN | 200 | 43 | 14.0% |
| Mitchellville, TN | 160 | 43 | 14.0% |
| Bransford, TN | 269 | 43 | 14.0% |
| Portland, TN | 12,928 | 43 | 14.0% |
| Graball, TN | 105 | 45 | 10.0% |
| City | Population | Air Quality Index | National Avg. |
| Buckeye, IA | 105 | 37 | 26.0% |
| Tingley, IA | 105 | 39 | 22.0% |
| Unionville, IA | 105 | 39 | 22.0% |
| Lima, IL | 105 | 41 | 18.0% |
| Raglesville, IN | 105 | 1 | 98.0% |
| Graball, TN | 105 | 45 | 10.0% |
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