| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 35°F | 48°F | 42°F | 5.6" |
| February | 37°F | 51°F | 43°F | 3.7" |
| March | 39°F | 55°F | 46°F | 5.1" |
| April | 42°F | 60°F | 50°F | 3.2" |
| May | 47°F | 68°F | 56°F | 2.2" |
| June | 52°F | 72°F | 61°F | 1.5" |
| July | 56°F | 80°F | 66°F | 0.6" |
| August | 56°F | 80°F | 66°F | 1.1" |
| September | 53°F | 73°F | 61°F | 1.9" |
| October | 46°F | 62°F | 53°F | 4.5" |
| November | 40°F | 53°F | 46°F | 7.1" |
| December | 35°F | 47°F | 41°F | 6.1" |
| Index | SeaTac | Washington | National |
| Air quality index | 45 | 36 | 42 |
| Pollution index | 1,081,430 | 4,541,850 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 236 |
| Days with moderate air quality | 127 |
| Days w/ poor A.Q. for sensitive groups | 2 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Manchester, WA | 6,050 | 18 | 64.0% |
| Ruston, WA | 1,329 | 18 | 64.0% |
| Browns Point, WA | 961 | 18 | 64.0% |
| Gig Harbor, WA | 10,280 | 18 | 64.0% |
| Parkwood, WA | 6,758 | 18 | 64.0% |
| SeaTac, WA | 29,102 | 45 | 10.0% |
| City | Population | Air Quality Index | National Avg. |
| Fuquay-Varina, NC | 29,110 | 46 | 8.0% |
| Oak Ridge, TN | 29,124 | 53 | 6.0% |
| Southgate, MI | 29,129 | 56 | 12.0% |
| Rexburg, ID | 29,064 | 43 | 14.0% |
| Fredericksburg, VA | 29,059 | 47 | 6.0% |
| SeaTac, WA | 29,102 | 45 | 10.0% |
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