Hi, and welcome to Frog Forum!

For GTF, they are hardy, and will survive cold temperature (they will hibernate during Winter). So it should be fine. Here's a similar thread written not too long ago on a similar subject:

http://www.frogforum.net/tree-frogs/...bernation.html

And you could always refer to the GTF care sheet directly: http://www.frogforum.net/tree-frog-c...ysoscelis.html

Eric