Yes--our water barrels (and any FDA/USDA-standard barrels) will withstand being frozen solid. However, I'd ask you to think about how much help that will be to you if, when you need it, the water is frozen solid in a 55-gallon barrel. How will you thaw it out? You can't apply flame to it to thaw it (the plastic will melt) and it will be extremely heavy to move if you think you can at that point bring it indoors to thaw out (VERY) slowly.
I'd suggest finding room indoors for 15 or 30 gallon barrels (which can usually fit in a closet). That way, the water will be accessible and a practical prep for you year-round.