I suppose if you use it fast enough it might not be a problem. >Vermouth is a fortified wine, which means that once you open the bottle, it will begin to oxidize. So how to store vermouth is simple but important. Vermouth should be refrigerated once opened to help slow down the oxidation process and extend the life of the liquid. As I said I like my wine chilled, so it all goes in the fridge. If truth be known, I'm such a freak that I shove everything in there, even stuff that traditionally doen't need refrigeration.