I've been using Bee Cozys for 5 years and they have really worked up in the New England Winters. I make sure they're rolled back top so the air can get under the top cover and then use a long sheet rock screw above the opening to keep the Cozy from covering the opening. I have never had any problem with moisture in the hive and I live near the ocean. I've tried plastic bags with leaves, hay stacked up and wind breaks, and foam insulation,but settled on the Bee Cozys.