There are actually cases of people getting SAD from the over abundance of sunlight in the summer (http://cliffmass.blogspot.com/2012/10/depression-from-too-mu...)
http://www.seattleweatherblog.com/rain/record-dryness-windin...
I used to live a few hundred kilometers away from Seattle in the same temperature area, I can say for sure I'm looking forward to this summer!