Durin's Day

Durin's Day was the Dwarves' New Year, reckoned as the first day of the last moon of autumn on the threshold of winter, and it was held to fall properly only when the last moon of autumn and the first sun of winter stood in the sky together. Since a lunar cycle runs about twenty-nine and a half days, that day could land anywhere between about the twenty-second of November and the twenty-first of December by a modern reckoning. Tolkien's own working notes, however, set it on the nineteenth of October, which puts the start of winter for the Dwarves of Erebor at the beginning of November.