No question about it, thunderstorms found in the rest of the country produce tremendous rainfall that can lead to dangerous flash flooding. Both types of rain have their special hazards. In the NW hypothermia is a real risk any time of year because, once wet, clothing and gear will probably never get dry and because the temperatures are relatively cool.

My original point about rain in the NW is that, unlike in other places, one cannot assume it will stop any time soon.

I live on the Pend Oreille River in the Selkirk Range in northeast WA, which is a part of the northern Rockies, and our weather reflects that. But I lived most of my life--and had most of my hiking experience--on the wet, west side of WA. I much prefer the drier side.