In the US we have a tradition every winter on the second of february where we check to see if a groundhog saw his shadow. If he did there are supposed to be 6 more weeks of winter. Id like to see an event simular to this, instead of 6 weeks it could be 7 days. It could happen in any season with an increased chance in the winter. It could be set to happen on a certain day of the month so as to give the player a chance to know in advance. This would be a double edged sword, adding an extra risk vs reward element to the game. If the player planned for the potential event happening in the winter gathering more food for their animals etc. you would gain 7 more days to do things like mining fishing gathering resources socializing etc. In the seasons that are not winter you could get 7 more days to grow crops. if you didnt want the extra days just sleep them off. This could also add a leap year element to the game as well since some years you could have an extra week in them. Challenging npcs could be added later whose birthdays were on a specific season's leap week making them more difficult to befriend/marry.