What kind of question is that? Well, if you are storing those curtains in an unheated attic or garage you might be in for an expensive surprise in the spring.
When subjected to extreme cold those vinyl curtains become as brittle as a potato chip and actually can collapse and shatter from their own weight.
Vinyl curtains should be stowed for the winter in a warm room. And, always store them flat on a non-abrasive surface, or roll them loosely. Never fold the vinyl.