Where I live we have a bunch of small holidays in the spring. Winter only has the one big one. Spring seems more the season for them

Seconding Obsidian - it’s not FOSS, but the files are just markdown, nothing special, so you’re not locked in. Self hosting is real easy, you just have to Sync the files, and everything follows. I use syncthing between my laptop and phone and am having a good time with it.