I have a series of bi-monthly nights where neither of my planets two moons are visible, called Fireflies Eve, and in this year's calendar my shortest day lands on a double new moon, so it's a rare and special version of fireflies eve. I haven't figured out how I should make it more interesting yet, but it's something I've been pondering. Typical Fireflies Eve is full of big bonfires and paper candle kites or whatever they're called. So this one feels like something I should do more for.
RE: Worldbuilding Weekend Prompt #142 - Winter Solstice