Close Drafts with Caulk
If the old caulk on the window is ineffective in insulating the window or there are drafts that need to be filled, caulking can help keep the wind and cold out. The wind slides in from these gaps and lowers the temperature of your house, if you plan on caulking in winters, you may not be able to do it on a cold day. Caulking the windows is best done before the arrival of winter because the temperature should be 45 degrees Fahrenheit or higher to cover the drafts. Hence, the best time is a sunny day if it's winter already.
Draft Snake
Draft snakes are DIY snakes made of an old legging or arms of a sweater filled with dry ice, or cotton. They are fit inside drafts and space between the sliding windows. They help keep the wind as well as dust and insects out.
Plastic Sheets
Thick plastic sheets on windows can stop the air from coming into the house. Some people also use bubble wraps to insulate the windows because they block the entrance of air and are easy to use. To effectively winterize the window with a plastic sheet or bubble wrap, cut the sheet according to the size of the window. Tape it to the wall avoiding any untapped spots. If you are using a thin plastic sheet or bubble wrap, use a blow-dryer to heat and stick the sides of the plastic sheet to the window frame.
