| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 33°F | 46°F | 39°F | 3.0" |
| February | 34°F | 50°F | 41°F | 1.7" |
| March | 37°F | 54°F | 45°F | 3.4" |
| April | 40°F | 59°F | 48°F | 2.0" |
| May | 45°F | 65°F | 54°F | 2.4" |
| June | 49°F | 70°F | 59°F | 1.9" |
| July | 52°F | 77°F | 63°F | 1.3" |
| August | 52°F | 78°F | 63°F | 1.4" |
| September | 49°F | 71°F | 58°F | 2.4" |
| October | 43°F | 60°F | 50°F | 3.4" |
| November | 37°F | 52°F | 44°F | 4.0" |
| December | 32°F | 44°F | 38°F | 3.1" |
| Index | Arlington | Washington | National |
| Air quality index | 24 | 36 | 42 |
| Pollution index | 15,778,900 | 4,541,850 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 361 |
| Days with moderate air quality | 4 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.270% |
| Carbon Tetrachloride | 0.040% |
| Lead | 0.160% |
| Mercury | 0.003% |
| City | Population | Air Quality Index | National Avg. |
| Canyon Creek, WA | 3,218 | 24 | 52.0% |
| Lake Cavanaugh, WA | 220 | 24 | 52.0% |
| Lochsloy, WA | 2,991 | 24 | 52.0% |
| Silvana, WA | 14 | 24 | 52.0% |
| Lake McMurray, WA | 478 | 24 | 52.0% |
| Arlington, WA | 19,947 | 24 | 52.0% |
| City | Population | Air Quality Index | National Avg. |
| Rio Rico, AZ | 19,948 | 31 | 38.0% |
| Camrose, AB | 19,951 | n/a | |
| Rosedale, MD | 19,963 | 46 | 8.0% |
| North Ogden, UT | 19,930 | 45 | 10.0% |
| Havelock, NC | 19,927 | 37 | 26.0% |
| Arlington, WA | 19,947 | 24 | 52.0% |
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