| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 31°F | 51°F | 40°F | 4.1" |
| February | 33°F | 53°F | 42°F | 3.4" |
| March | 41°F | 65°F | 52°F | 5.8" |
| April | 50°F | 74°F | 62°F | 5.8" |
| May | 58°F | 81°F | 69°F | 6.0" |
| June | 67°F | 89°F | 77°F | 4.8" |
| July | 69°F | 91°F | 79°F | 4.2" |
| August | 68°F | 91°F | 79°F | 3.0" |
| September | 61°F | 85°F | 72°F | 3.6" |
| October | 48°F | 74°F | 60°F | 3.5" |
| November | 39°F | 63°F | 50°F | 4.0" |
| December | 34°F | 53°F | 43°F | 5.5" |
| Index | Somerville | Tennessee | National |
| Air quality index | 45 | 76 | 42 |
| Pollution index | 20,539,300 | 2,454,916 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 221 |
| Days with moderate air quality | 139 |
| Days w/ poor A.Q. for sensitive groups | 5 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.060% |
| Benzene | 0.210% |
| Carbon Tetrachloride | 0.060% |
| Lead | 0.170% |
| Mercury | 0.110% |
| City | Population | Air Quality Index | National Avg. |
| Hickory Valley, TN | 86 | 27 | 46.0% |
| Whiteville, TN | 4,482 | 27 | 46.0% |
| Grand Junction, TN | 388 | 45 | 10.0% |
| Williston, TN | 537 | 45 | 10.0% |
| Mason, TN | 1,120 | 45 | 10.0% |
| Somerville, TN | 3,257 | 45 | 10.0% |
| City | Population | Air Quality Index | National Avg. |
| Russell, KY | 3,257 | 42 | 16.0% |
| Thompson-Nicola L (Grasslands), BC | 3,257 | n/a | |
| El Verano, CA | 3,256 | 35 | 30.0% |
| Attica, IN | 3,256 | 42 | 16.0% |
| Berwyn Heights, MD | 3,256 | 47 | 6.0% |
| Somerville, TN | 3,257 | 45 | 10.0% |
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