I would have to guess a type of garter or ribbon snake(Thamnophis sp.) due to the double row of alternating black spots and well defined stripes (from a book I have) and due to your area and the fact that garter snakes are tolerant of colder weather. I would be hard pressed to pin it down specifically, there are so many color variations among garter snakes. It looks exactly like all the garter and ribbon snake pictures I have if you just substitute different colors. I could be totally off base though

What color is the belly of the snake?
Best I can do
Alan