It's a 'mild' climate... In that you will never see negative temperatures in the winter, and in the summer you'll never see temperatures over 95ish.... (yes it does happen in rare circumstances)....
You also rarely see snow during the winter (this year being a huge exception).. Depending on where you live (in the foothills or near the Sound), you'll probably only get up to 3 inches of snow a year (again, greatly depends on where you live).
It definitely is fairly drizzly/gloomy there throughout the year, but if it wasn't for this, the state wouldn't be so gorgeous.... By gorgeous I mean very very lush and green. The forests up on the Olympia Peninsula are breathtaking.
Simply put, Washington State is an outdoorsman's paradise. It is a unique state in that you are never more than a 3-4 hour drive away from a completely different climate... Eastern Washington is completely different from Western Washington... Separated by the Rockies, Eastern Washington is more like a desert.... Essentially you have the ocean, rainforest, mountains (lots of good snow and world class skiing/snowboarding), and desert within an arms reach.
Anyways... that's all I've got.