In the Shire Calendar, the year's final month was known as Foreyule, the month before the festival of Yule. In the calendar of Bree, however, it had a different name, 'Yulemath', meaning simply, 'month of Yule'. This usage was not confined to Bree: the same traditional name was still used in the eastern parts of the Shire.
The Hobbits' calendars were so arranged that Yulemath would always begin on the same weekday (a Hevensday or Wednesday), and also end on the same weekday (a Mersday or Thursday). It was immediately followed by the first of the two Yuledays, which was the final day of the year.