No, I wouldn't be surprised how dry it gets in the winter (inside the house - because of forced air heating). However, I have a humidistat, and this winter it never dropped out of the comfort zone (roughly 35% to 50% humidity). When it does, I have a humidifier that I use. I didn't use it at all this winter.
35% to 50% humidity is dry for us, and our wooden doors do dry out and close properly. When my sister visits (she lives in Pleasanton, CA, one valley over from SF, and in a dry climate) she constantly whimpers about the humidity, even when it's in the comfort zone. Right now, inside, it is 68.7 degrees, 60% humidity, all windows closed. We have a relatively humid climate. UGH!
