Now is the time to seal up any old or disfuntional windows that may be causing a cold breeze to flow through your house or shed.So what are some ways that you can winterize your windows you may ask? Here are some suggestions on winterizing your windows this season.
First step is to begin caulking around the outside of the window. To start you first begin by using a putty knife to scrape off any old caulk or peeling paint from around the exterior perimeter of the window. Next, clean away all dirt around the outside of the window. Wipe the surfaces dry with a clean cloth.
Now for the caulking. Apply fresh caulk around the outside perimeter of the window, creating a seal between the window frame and siding.Exterior-grade caulk is the ideal type that you would use for this type of job. 
The step after caulking would be to move inside and use weatherstripping to seal around the edges of the moveable part of the window. You can weatherstrip with a variety of items. Here are some suggestions on some material that does the job:
Adhesive-backed foam: It has easy peel-and-stick application and cuts easily with scissors.
Tubular rubber-gasket:
weatherstripping: This is similar to adhesive-backed foam, except that it's formed into a hollow rubber tube instead of dense foam.
Felt: Felt is one of the oldest types of weatherstripping. It's commonly sold in rolls with or without an adhesive backing and is also available with an attached metal mounting flange.
Window insulation kits: Block cold air by sealing the entire window behind a large sheet of plastic wrap. The plastic adheres to the interior window. You then use a blow dryer to seal it in place. Keep in mind that you won't be able to open the window until next spring, when you peel off the plastic wrap.