| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 37°F | 45°F | 41°F | 3.1" |
| February | 39°F | 47°F | 43°F | 2.8" |
| March | 42°F | 52°F | 46°F | 2.3" |
| April | 44°F | 55°F | 49°F | 1.2" |
| May | 47°F | 60°F | 53°F | 1.1" |
| June | 50°F | 64°F | 56°F | 1.0" |
| July | 53°F | 66°F | 58°F | 0.7" |
| August | 52°F | 68°F | 59°F | 2.2" |
| September | 49°F | 63°F | 55°F | 1.7" |
| October | 46°F | 57°F | 51°F | 4.7" |
| November | 42°F | 51°F | 46°F | 5.8" |
| December | 37°F | 45°F | 41°F | 4.7" |
| Index | Sequim | Washington | National |
| Air quality index | 34 | 36 | 42 |
| Pollution index | 1,626,160 | 4,541,850 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 341 |
| Days with moderate air quality | 24 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.005% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.020% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Port Townsend, WA | 9,710 | 24 | 52.0% |
| Bell Hill, WA | 762 | 34 | 32.0% |
| River Road, WA | 718 | 34 | 32.0% |
| Blyn, WA | 45 | 34 | 32.0% |
| Port Angeles East, WA | 3,339 | 34 | 32.0% |
| Sequim, WA | 7,441 | 34 | 32.0% |
| City | Population | Air Quality Index | National Avg. |
| Georgetown, DE | 7,436 | 36 | 28.0% |
| Scappoose, OR | 7,436 | 38 | 24.0% |
| Ellwood City, PA | 7,436 | 31 | 38.0% |
| Whitinsville, MA | 7,435 | 40 | 20.0% |
| Clarkston, WA | 7,435 | 29 | 42.0% |
| Sequim, WA | 7,441 | 34 | 32.0% |
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