How do I stop cold air from coming through my bedroom window?

Caulk around the windows on both sides of the trim. If they are single pane, you can add storm windows or plastic. Add thermal curtains. Blinds may help as well.

Get some black out curtains or buy some black out fabric and place against the window. Also make sure the windows are properly caulked. You can also use bubble wrap against the window if you are in a cold climate for the winter.

Weatherstripping is where I would start. How old are the windows?

Hi Lester, if you want to keep the draft out, you could use bubble wrap to cover the windows. Or heavy drapes or a quilt?

Take a look at this link: https://dengarden.com/home-improvement/How-to-Bubble-Wrap-Windows

Bubble wrap cut to fit the windows glass..a squirt of water will hold it in place. Put caulking arround the window frame, cover with a sheet of plastic from a weatherizing kit. The plastic is thin and clear, and you will need need the double backed tape to secure it.

Hope this helps you:

https://www.thespruce.com/drafty-windows-6500135