Still not directly to do with the why of seasons either, but anyway: the Vikings had a "blót", i.e. sacrifice, several times a year to the gods, one in midsummer, one after the harvest season to thank for a good harvest, and most importantly one around the winter solstice, "jól", for the harvest season to come. Blót is related to blood, which they drank. Christmas is still called "jul" here, from pre-Christian times. You can find details on Wikipedia more than I know

But a funny spinoff is the tradition that still exists of putting out a bowl of porridge (thick, creamy rice porridge, good stuff!) to the "nisse" at Christmas. Today Santa Claus is also called a nisse (julenissen), but the original nisse was a small grey-bearded elf living in the barn, the guardian of the household, and the porridge was his traditional sacrifice. If you didn't put out porridge for him he could think up all kinds of mischief on a traditional farm, sour the milk, lame the cows, stuff like that. Nothing large and magical like affecting the seasons though.