| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 28°F | 43°F | 36°F | 1.0" |
| February | 30°F | 49°F | 39°F | 1.0" |
| March | 35°F | 57°F | 45°F | 1.6" |
| April | 39°F | 65°F | 51°F | 1.4" |
| May | 46°F | 75°F | 60°F | 1.5" |
| June | 53°F | 82°F | 67°F | 1.3" |
| July | 60°F | 95°F | 77°F | 0.3" |
| August | 59°F | 93°F | 76°F | 0.4" |
| September | 51°F | 82°F | 66°F | 0.6" |
| October | 42°F | 66°F | 53°F | 1.1" |
| November | 33°F | 51°F | 42°F | 1.3" |
| December | 27°F | 41°F | 34°F | 1.4" |
| Index | Clarkston | Washington | National |
| Air quality index | 29 | 36 | 42 |
| Pollution index | 3,385,410 | 4,541,850 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 291 |
| Days with moderate air quality | 73 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.030% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.040% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Colton, WA | 372 | 18 | 64.0% |
| Sweetwater, ID | 264 | 29 | 42.0% |
| Uniontown, WA | 273 | 29 | 42.0% |
| Genesee, ID | 1,209 | 29 | 42.0% |
| Asotin, WA | 1,168 | 29 | 42.0% |
| Clarkston, WA | 7,435 | 29 | 42.0% |
| City | Population | Air Quality Index | National Avg. |
| Whitinsville, MA | 7,435 | 40 | 20.0% |
| Montpelier, VT | 7,434 | 37 | 26.0% |
| Georgetown, DE | 7,436 | 36 | 28.0% |
| Scappoose, OR | 7,436 | 38 | 24.0% |
| Ellwood City, PA | 7,436 | 31 | 38.0% |
| Clarkston, WA | 7,435 | 29 | 42.0% |
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