Good question, Angie! I think there were a few factors:
weather consistency - Seattle tends to have a month of highs in the 40s, followed by a month of 50s, a few months of 60s, 70s, maybe 80s, and then back down in a lovely, flowing cycle. There are sometimes outliers, but it's nothing like here where we suddenly have a day or two in the mid-70s in February, followed by brutal sub-zero temps the following week. I relish that fickleness, but I don't like dressing for it.
rainy days - I love love loved throwing on a trench coat and heading out on a rainy day. I always felt fab. We don't really have those here. Our rain comes in evening thunderstorms and afternoon downpours. You don't dress for it, so much as find shelter until it's over. I think I'm the only person I know who even owns a trench.
fashion culture - I know Seattle is a very casual city, but there was enough diversity, I never felt overdressed there. I often feel overdressed here, even in the very casual outfits you've seen me in. I wore that jeans-converse-blazer combo to parents' night on Monday, and was one of very few parents not in flip-flops, shorts, and a tee. Some of this also has to do with the urban vs small-town factor, as well.