Bone, It normally is the other way around,horn will absorb moisture so it's imparative to try to keep them dry. Wet billets ain't much good. Humid weather is tough on them ,makes them soft. One can microwave them to dry them out, I run a dehumidifier in my shop to help out with this. My fav billet was from a barn wall that had been weathered for many years,(palms were all cracked) it works great.
I have a buddy that has a small battery powered dehumdifier that fits in a 5 gallon bucket,he keeps him billets in it during humid weather.