I've noticed that a few states have passed "hurricane" sales tax holidays. The idea is to allow and encourage residents to stock up on this kind of stuff before the need actually arrives. This seems like an eminently acceptable idea and, for what it's worth, the Sales Tax Guy encourages it. So call your governor and tell him or her that the Sales Tax Guy thinks this is an A plus idea.
Based on a quick survey, it looks like the current list is Virginia, Louisiana and Florida.
Sales Tax Guy