I would guess it depends on the chameleon you have. I only have 2 panthers and I have been told high 60's-low 70's would be the coldest to put them out, and then only if it's an adult.
From what I understand, and I probably am wrong, but Jackson and similar species are from mountainous areas and can tolerate cooler temps.
What part of NC? That's a state with a broad range of temps...from the coastal to the mountains.