| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 24°F | 37°F | 30°F | 2.8" |
| February | 28°F | 46°F | 35°F | 2.1" |
| March | 34°F | 54°F | 43°F | 2.0" |
| April | 36°F | 59°F | 47°F | 1.8" |
| May | 43°F | 69°F | 55°F | 2.0" |
| June | 46°F | 73°F | 59°F | 2.0" |
| July | 51°F | 88°F | 70°F | 0.9" |
| August | 48°F | 86°F | 67°F | 1.2" |
| September | 41°F | 73°F | 56°F | 1.4" |
| October | 39°F | 61°F | 49°F | 2.4" |
| November | 31°F | 45°F | 37°F | 2.7" |
| December | 24°F | 35°F | 30°F | 2.9" |
| Index | Colfax | Washington | National |
| Air quality index | 18 | 36 | 42 |
| Pollution index | 1,232,200 | 4,541,850 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 354 |
| Days with moderate air quality | 11 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.020% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Palouse, WA | 969 | 10 | 80.0% |
| Pullman, WA | 33,974 | 18 | 64.0% |
| Albion, WA | 677 | 18 | 64.0% |
| St. John, WA | 612 | 18 | 64.0% |
| Garfield, WA | 586 | 18 | 64.0% |
| Colfax, WA | 2,879 | 18 | 64.0% |
| City | Population | Air Quality Index | National Avg. |
| Weedpatch, CA | 2,879 | 67 | 34.0% |
| Indialantic, FL | 2,879 | 36 | 28.0% |
| Kilauea, HI | 2,879 | 13 | 74.0% |
| Falmouth, KY | 2,879 | 54 | 8.0% |
| Bucksport, ME | 2,879 | 31 | 38.0% |
| Colfax, WA | 2,879 | 18 | 64.0% |
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