Lisa, up here in the frozen wastes, any water trapped in the cover will damage it, and the extreme cold makes it terribly brittle. You'll be lucky if the cover actually survives the winter. I frequently get a foot or more solid raft of ice in my pool. We had snow as "high as an elephant's eye!"

Covering it in the summer is important, I have a "Solar cover cover" that's merely a long, white sheet of plastic that works.