It's impossible to tell if you should keep your orchids away form the window because we do not know what your growing conditions are like or how cold it will get when the cold front moves through.
As long as the temps stay within the ranges perscribed by your culture sheet they'll be fine. If you don't yet have cultural info on how to grow your orchids, go to the AOS website (
American Orchid Society) and get a Dendrobium culture sheet.