Be sure and get some desiccant to go in with your fabrics. I made the mistake of storing our christmas ornaments in our basement and even though they were in plastic tubs with tight fitting lids, some of the fabric ones got mildewy and had to be cleaned--what a pain. If I'd put some of those silica gel packets in with them it probably wouldn't have happened. I can imagine it could be a serious problem if you've got a large stash and you are moving to a hot/humid locality.
I would not store the machines in the garage if there is another space in the house for them. Since the garage is not heated/cooled I would be concerned not only about excessive heat, but also about moisture from ambient humidity.
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