Kevin,
Where I live it's generally is 80-90% humidity for 5 months, less than 50% for 5 months and a couple of months of all over the place. With these long periods the basses absorb or lose a lot of moisture. In particular my fretless is affected since I keep a close to flat neck and low action. Likewise my BB has medium low action and what I consider minimal relief. I only have to adjust twice a year more or less. Generally a 1/4 to 1/2 turn and it is done. My 5 string Orion really could get by without adjustments since I need more relief and a higher action to handle the B string. I also have a couple of non-Alembic basses that I can see the movement in at the season change. On one of them it is no big deal due to it's setup. On the other it's a quick tweak. When I lived in the Chicago and SF Bay areas I don't recall these other basses moving around. However where I lived in the Bay area was pretty stable humidity wise and Chicago never had as long and as humid a summer as here.
My house has similar behavior. Between summer and winter I have several places where you can see the house expand and contract by a 1/4 - 3/8 inches. None of it is a big deal to me. I just look at as part of living in the south.
Keith
