I've been to the Quillayute area (the Olympic national park) and it is a little "damp".
I suspect we were the last people up the Hoh River (which flows into the Pacific a little south of Quillayute) the year we visited, as we were alone at the upper campsites (more 'approved places to pitch a tent' than anything) and only a day or two after we got out, 15 inches of rain fell in a day, washing out all the trails, bridges, trees etc etc and closing the place until the following spring (this was in October). There were at least 4 inches on the day we walked out, and I remember the town of Forks being awash.
I think that it it reasonably dry in the summer though, so it will be interesting to see if it can beat western Scotland or Alaska over a whole year.
In the US it is heralded as their 'rainforest' - albeit a temperate one. We have very similar temperate rainforest habitats in W Wales, Devon and particularly Scotland, but without the huge Sitka and Douglas Fir, although where these have been planted in the 19th century and left to grow there is a distinct resemblance. The Tongass in Alaska is the largest unmessed with (for now) version of this habitat.
As you (BDG) like to post some info on locations, I'll post a couple of pictures here to give you an idea of the natural habitat of the area - hope this is OK. The first could be somewhere in 'Boggy Britain', the second probably not!
This post has been edited by Tim Prosser: 06 January 2012 - 12:59