January 2028 has 31 days. The 1st falls on a Saturday and the 31st on a Monday, so the grid runs to 6 rows.
Federal holidays this month: New Year's Day on January 1 (a Saturday), and Martin Luther King Jr. Day on January 17 (a Monday).
Holiday names print inside the day cell, wrapped to fit rather than running across the rule into the next day.
The week runs Sunday to Saturday, the usual US arrangement.