I have a garage where the temperature in winter ranges around 15C, quite constantly. No fridge, as I said before. If I put the faunaboxes in the balcony, shielded by direct sunlight, the temperatures are a bit lower, at night about the 5-10C (44-50F) range, no higher than 15C a day. Is that enough?

The specie is, or better should be Thamnophis Sirtalis, but apparently here in the forum there is some debate. There is another post of mine where I was told they are Ribbon snakes, not garters, so Thamnophis sauritus, I do not know if easterns or notherns...