Winter weather reflects Winter's state of mind and heart. If it's cold with a typical amount of cold and bluster she's having a grand season. If it's unseasonably warm, not enough snow, too cold it means something has upset her.
Think back on the winter we've had so far (well, okay, it's still fall but it is December!) and come up with a story that explains it. Is she upset with someone, perhaps one of the previous seasons? Does she depend on others to create winter effects? Clouds? Wind? The snow fairies? The frost elves? Are they not cooperating? Why?