Cold shuts down almost every single natural life cycle we have come to expect to be there in the morning when we wake up. It's the interglacial that is weird and unnatural. Grasshoppers are shooting around breeding like crazy and chewing and spitting and leaping and fluttering around in an orgy of sound and fury that signifies nothing in a blaze of heat and light and fertility.
Then the cold returns. It gets quiet enough to hear yourself think again. If you survive.