| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 32°F | 47°F | 39°F | 7.3" |
| February | 32°F | 51°F | 41°F | 4.8" |
| March | 35°F | 55°F | 44°F | 7.0" |
| April | 36°F | 61°F | 48°F | 3.5" |
| May | 42°F | 68°F | 55°F | 2.7" |
| June | 47°F | 73°F | 59°F | 1.5" |
| July | 50°F | 80°F | 64°F | 0.6" |
| August | 50°F | 81°F | 64°F | 1.0" |
| September | 46°F | 74°F | 59°F | 2.5" |
| October | 41°F | 62°F | 51°F | 5.5" |
| November | 35°F | 52°F | 44°F | 9.7" |
| December | 31°F | 46°F | 38°F | 8.0" |
| Index | Goldcrest | Olympia | Washington |
| Air quality index | 30 | 30 | 36 |
| Pollution index | 6,704,330 | 6,704,330 | 8,596,989 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 323 |
| Days with moderate air quality | 42 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.003% |
| Benzene | 0.100% |
| Carbon Tetrachloride | 0.004% |
| Lead | 0.030% |
| Mercury | 0.003% |
| City, State | Population | Air Quality Index | National Avg. |
| Tenino, WA | 1,744 | 20 | 60% |
| Home, WA | 1,531 | 21 | 58% |
| Shelton, WA | 9,832 | 21 | 58% |
| Herron Island, WA | 67 | 21 | 58% |
| Anderson Island, WA | 1,150 | 30 | 40% |
| Olympia, WA | 49,608 | 30 | 40% |
| City, State | Population | Air Quality Index | National Avg. |
| Wilson, NC | 49,558 | 36 | 28% |
| Downers Grove, IL | 49,555 | 55 | 10% |
| Poway, CA | 49,675 | 64 | 28% |
| Logan, UT | 49,539 | 44 | 12% |
| Ashburn, VA | 49,692 | 47 | 6% |
| Olympia, WA | 49,608 | 30 | 40% |
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