Summer officially begins on 1 December, and by 25 December 2028 the country runs its hottest, longest-daylight stretch of the year. December closes 2028 in the fourth calendar quarter, the final quarter under the standard January-to-December system used on this page.
Monday 25 December 2028 is the first working day of its week. Any bill, deadline or rostered task set for the preceding Saturday or Sunday moves to this date under standard business-day rules, and the working-day count above treats it as day one of a fresh five-day working stretch that runs through to Friday, before the weekend resets the cycle again.
2028 has 366 days on the calendar. Leap years add a single extra day to February, giving those years 366 days instead of 365 and shifting the day-of-year number for every date from March onward by one compared with an ordinary year. This is the only irregularity in the length of the Australian calendar year.