| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 36°F | 46°F | 41°F | 2.9" |
| February | 35°F | 49°F | 41°F | 1.9" |
| March | 38°F | 52°F | 45°F | 2.3" |
| April | 41°F | 55°F | 47°F | 2.0" |
| May | 46°F | 60°F | 52°F | 1.8" |
| June | 50°F | 63°F | 55°F | 1.8" |
| July | 53°F | 68°F | 59°F | 0.7" |
| August | 53°F | 68°F | 59°F | 1.5" |
| September | 49°F | 65°F | 56°F | 1.4" |
| October | 45°F | 58°F | 51°F | 1.8" |
| November | 40°F | 51°F | 45°F | 3.5" |
| December | 35°F | 46°F | 40°F | 2.2" |
| Index | Coupeville | Washington | National |
| Air quality index | 24 | 36 | 42 |
| Pollution index | 1,626,160 | 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 | 0.005% |
| 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% |
| Freeland, WA | 1,883 | 24 | 52.0% |
| Marrowstone, WA | 943 | 24 | 52.0% |
| Whidbey Island Station, WA | 2,375 | 24 | 52.0% |
| La Conner, WA | 974 | 24 | 52.0% |
| Coupeville, WA | 1,850 | 24 | 52.0% |
| City | Population | Air Quality Index | National Avg. |
| Bridgton, ME | 1,850 | 31 | 38.0% |
| Pumpkin Center, NC | 1,850 | 37 | 26.0% |
| Parkersburg, IA | 1,849 | 39 | 22.0% |
| Prague, OK | 1,851 | 36 | 28.0% |
| Ridgeville, SC | 1,849 | 29 | 42.0% |
| Coupeville, WA | 1,850 | 24 | 52.0% |
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