I run a dehumidifier in my insulated unconditioned garage. Keeps the humidity in a decent range. You'd be amazed how much it pulls out of the air after a rain.
Just curious though, has anyone tried those tool covers/blankets that are supposed to prevent rust? I think that htc sells some.
No but I had left a blanket over part of my saw, coincidence, it made no difference. There was rust under the blanket and beside it.