Given its traditional name, December's full moon is associated with a negative aspect of the month — the cold, dark, long nights, specifically. One can see this as a natural (if less-than-cheery) symbol for this month's moon, but it can also be an opportunity to step back and consider other sources of warmth and light in your life. Just as the Winter Solstice brings people together, you may recognize that, during the colder months of the year, you seek comfort among friends and family.
These feelings may be stronger than usual this year, as the maternal and familial influence of the full moon may intensify your desire to be around loved ones for the holidays. Other spiritual effects of the full moon (clarity of mind and heart, heightened psychic awareness, a greater capacity for healing) can be beneficial for your end-of-year reflections, and even help you set intentions for 2016. With this in mind, even your Christmas well-wishes can be imbued with the power of the full moon now.
Christmas is supposed to be a time of giving, charity, and goodwill. The full moon can bring unexpected things about yourself to light. If simultaneously observed, the collision of these two events (the holiday and the full moon) will usher in a truly advantageous moment to reevaluate our place in the world and our relationships with those we care about.