January 2027 has 31 days. The 1st falls on a Friday and the 31st on a Sunday, so the grid runs to 6 rows.
Federal holidays this month: New Year's Day on January 1 (a Friday), and Martin Luther King Jr. Day on January 18 (a Monday).
Nothing but dates and rules, which leaves the most room to write in.
The week runs Sunday to Saturday, the usual US arrangement.