Shen hybrid basses

[Wyatt Newman]

I have corresponded with Steve Sprague at CSC a couple of times in the last few days concerning the stability of the Shen Willow flatbacks. He has noted that they had expected more problems with cracking than they have received and some time ago had experimented with X bracing lenths and placement until they feel that the construction is optimum to prevent this problem. He warns though, that sudden and sharp temperature extremes should be avoided and that dry winter conditions with low humidity would necessitate the use of dampits. I have a question about that.
I live in the deep and humid south. Our winters are dry sometimes. For you guys in the know, what percentage would be considered "low" humidity conditions?