why is my snail hibernating when its so hot

just found my garden snail microplastic hibernating (he's got a thin dry whiteish layer covering the entrance of his shell) after not seeing him for a week cause he was buried. I know snails hibernate when its too cold, do they also do it when its hot? I'm in the southern hemisphere so it's the middle of summer here. Another possibility is that its too dry, a few weeks ago I changed the soil from the dirt in the area I found him in to coco fibre which seems to dry out much quicker. Sometimes the top layer of the soil is dry by the end of the day. should I be spraying it twice a day now? Theres another snail in there as well also a garden snail but he's fine and as active as usual.