Oregon is a near perfect climate in spring and summer for marijuana, but the fall is just too dang wet. There is a ton of both powder mildew (which attacks the leaves) and bud rot that starts from the inside of the buds. The bud rot is the worst, if you miss that it is attacking the insides of your buds for a few days you can pretty much lose your whole harvest before it even is visible at the surface of the buds. Particularly if they are dense/tightly packed colas.