While storing bows in my shop the humidity was up to 70-80% if I remember right, during this time. It was a couple months and I wanted to see if the heat treating method would prevent hickory from taking on moisture. They got back up to 6-8% moisture content and cast took a hit. But after being in heat box a while, it returned.
I don't have exact numbers on humidity, temperature and moisture content with me but do believe I got it in my logbook at home.
I've read somewhere you should store @50% humidity but have never tried it longterm as I just revert back to osage since it doesn't seem to matter with it.