Just know that the weather isn't great, but when it is, it's awesome. You're going to get a snow storm, maybe two, during the entire winter. Besides that, it's rainy or at least cloudy 75% of the time from November through May. Temps usually drop down to low 30's for much of winter and are as high as mid-80's in the summer. I've been to quite a few cities in my life but a nice summer sunny day in Seattle honestly cannot be beat.
And I didn't even mention Vancouver BC and Portland are both within a couple of hours of Seattle and are both great cities.

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