This year will be the first full moon to occur on the winter solstice, Dec. 22, commonly called the first day of winter. Since a full moon on the winter solstice occurred in conjunction with a lunar perigee (point in the moon's orbit that is closest to Earth) The moon will appear about 14% larger than it does at apogee (the point in it's elliptical orbit that is farthest from the Earth) since the Earth is also several million miles closer to the sun at this time of the year than in the summer, sunlight striking the moon is about 7% stronger making it brighter. Also, this will be the closest perigee of the Moon of the year since the moon's orbit is constantly deforming.
Simply ~ Dec 22nd, when the moon is full, it will be in its closest position to the earth making it 14% larger; and the earth will be very close to the sun making it 7% brighter. Last time it happened = 133 years ago. In other words ~ the largest brightest moon you will ever see in your lifetime. It will be pretty bright that night. Won't happen again for over a hundred years.