Well, it's not cold like Alaska, but western WA tends to be cooler than the rest of the state. It does get high temps in the summer, but not excessive like AZ or TX.
There is higher humidity on the western side of the mountains, which is fine, because I like the green.
It doesn't snow alot (usually), two years ago we got dumped on with snow, the week before Christmas, which was perfect, IMO, but *lots* of people got stuck, because they're not used to driving in snow. Having grown up in eastern WA, where I'm used to snow, & having lived in CO, I loved driving in the snow.
We tend to get a bit of ice in the winter, because of the higher humidity, & it can be problematic, of course, but they're pretty good about putting the de-icer down when it's expected.
The main thing I do not like about western WA is the traffic. Anywhere in King County (where Seattle is), any of the main highways always have a good amount of traffic, & forget getting anywhere fast during rush hours....south Snohomish County (the county north) can be pretty hectic too.
But overall, I love WA & would not live anywhere else.