December 20th. Mother's Night comes from Scandinavian and Anglo-Saxon traditions. In the Norse tradition, this night celebrated the Dísir or ancestral mothers. The Dísir were the Old Ones: ancestral grandmothers who blessed, protected and provided prophetic counsel to the clan.
Today, December 20th is Mother's Night, the official beginning of the celebration of Yule.
The day before Winter Solstice
Mother Night is observed in honor of the Dark Goddess, who holds us at our beginnings and our endings. She may be the Black Madonna, Frigga, Freya, Holle, Hecate, the Cailleach, the Crone, or nameless. Also known as Mōdraniht, this night is Her doorway, after which the days of Yule can begin.