It should hold up just fine but you can call the company (listed on the label) and ask them. I have used glass paint but if there is a lot of rain and snow, I am not sure.
I see you are in Springfield . . . I just shipped some Christmas ornaments there last week. It gets cold and wet there so I would check before you purchase the paint.
Dick Blick is a place I buy paints and here is the link to the glass paint:
http://www.dickblick.com/categ...
The second section lists glass paints.