Christmas decoration on a patio? Extension cord???

Ready? You need duct tape.. run the cord thru the door then duct tape the opening.. it will keep out the weather and you will still see the pretty lights..

Wow, no outside outlets near the patio door? I'd go crazy, I'm always plugging stuff into my outside outlet on my patio.

Run it out of a window, put some foam rubber under the window and tape over any gaps that might let heat out. Maybe even sandwich the wire between 2 pieces of foam rubber so it doesn't contact metal if the window frames are metal.

This will be much better than running out the patio door since it will get a lot less use than the door.

An extension cord ging out of a door, particularly a metal door is not a good idea. You could seriously injure yourself, your daughter, or someone else if the door cuts the insulation on the cord. Please, find somewhere else to plug in your lights.