| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 29°F | 48°F | 37°F | 5.2" |
| February | 30°F | 51°F | 39°F | 7.4" |
| March | 38°F | 62°F | 49°F | 7.7" |
| April | 47°F | 73°F | 59°F | 7.8" |
| May | 55°F | 79°F | 66°F | 5.7" |
| June | 62°F | 86°F | 73°F | 6.7" |
| July | 66°F | 87°F | 75°F | 10.3" |
| August | 65°F | 87°F | 74°F | 5.1" |
| September | 60°F | 81°F | 69°F | 6.8" |
| October | 47°F | 72°F | 57°F | 10.0" |
| November | 36°F | 60°F | 46°F | 7.2" |
| December | 33°F | 51°F | 41°F | 10.2" |
| Index | Harlan | Kentucky | National |
| Air quality index | 39 | 45 | 42 |
| Pollution index | 7,824,360 | 1,369,131 | 2,726,193 |
| Measurement | Total |
| Days measured | 263 |
| Days with good air quality | 243 |
| Days with moderate air quality | 20 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.060% |
| Benzene | 0.070% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.070% |
| Mercury | 0.030% |
| City | Population | Air Quality Index | National Avg. |
| Coldiron, KY | 415 | 39 | 22.0% |
| Loyall, KY | 584 | 39 | 22.0% |
| Ewing, VA | 152 | 39 | 22.0% |
| Coxton, KY | 154 | 39 | 22.0% |
| Pathfork, KY | 266 | 39 | 22.0% |
| Harlan, KY | 1,411 | 39 | 22.0% |
| City | Population | Air Quality Index | National Avg. |
| Ignacio, CO | 1,411 | 44 | 12.0% |
| Strawberry Point, IA | 1,411 | 39 | 22.0% |
| Moravia, NY | 1,411 | 34 | 32.0% |
| Buchanan Dam, TX | 1,411 | 42 | 16.0% |
| Norton, NB | 1,411 | n/a | |
| Harlan, KY | 1,411 | 39 | 22.0% |
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