| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 24°F | 32°F | 27°F | 7.2" |
| February | 26°F | 38°F | 31°F | 2.7" |
| March | 31°F | 49°F | 38°F | 3.0" |
| April | 36°F | 60°F | 46°F | 1.9" |
| May | 44°F | 71°F | 56°F | 2.0" |
| June | 49°F | 76°F | 61°F | 2.2" |
| July | 55°F | 89°F | 70°F | 1.0" |
| August | 54°F | 88°F | 69°F | 0.7" |
| September | 47°F | 75°F | 59°F | 1.1" |
| October | 38°F | 56°F | 45°F | 2.7" |
| November | 31°F | 41°F | 35°F | 3.7" |
| December | 23°F | 31°F | 26°F | 6.5" |
| Index | Marcus | Washington | National |
| Air quality index | 43 | 36 | 42 |
| Pollution index | 2,800,290 | 4,541,850 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 252 |
| Days with moderate air quality | 111 |
| Days w/ poor A.Q. for sensitive groups | 2 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.020% |
| Benzene | 0.040% |
| Carbon Tetrachloride | 0.004% |
| Lead | 0.020% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Kettle Falls, WA | 1,594 | 43 | 14.0% |
| Barney's Junction, WA | 169 | 43 | 14.0% |
| Orient, WA | 82 | 43 | 14.0% |
| Barstow, WA | 49 | 43 | 14.0% |
| Boyds, WA | 52 | 43 | 14.0% |
| Marcus, WA | 181 | 43 | 14.0% |
| City | Population | Air Quality Index | National Avg. |
| Gulfcrest, AL | 181 | 42 | 16.0% |
| Humnoke, AR | 181 | 45 | 10.0% |
| Beaver Valley, AZ | 181 | 60 | 20.0% |
| Olancha, CA | 181 | 66 | 32.0% |
| Bristow, IA | 181 | 15 | 70.0% |
| Marcus, WA | 181 | 43 | 14.0% |
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