Interior window frosting means there is moisture in the cabin of the vehicle. Unless the outside air is very dry, leaving the windows open or cracked will probably make matters worse. Look for wet carpets caused by a clogged evaporator drain or another source of water intrusion, such as drain channels for doors, trunk lid, or sunroof, if so equipped. If the cowl or evaporator box is loaded with leaves or other debris, this can also cause an overwhelming amount of water to flow through the evaporator box during rain, causing the carpet to get wet. Dragging too much snow or water into the car from outside can also leave the carpets wet and cause interior window frosting. Try running your air conditioning to keep your cabin dry, even if it’s cold out. Leave the a/c on, but use the heat control to stay comfortable. You will still be warm, but the air will be dry, which will probably help a lot. You could also try supplementing that by cleaning the inside of the windows (dirty glass is more prone to collecting moisture, and they’re probably dirtier than you think, especially if you smoke) and using a fog preventing product on the interior glass. Rain-X makes a product for this purpose, but I don’t know how well it works since I’ve never used it. It may be worth a try, though.