Summer begins on 1 December, and December carries the two biggest fixed public holidays of the year: Christmas Day on 25 December and Boxing Day on 26 December. 11 December 2030 falls inside this 31-day month, at the height of the Australian retail and travel calendar for the year.
A public holiday landing on a Wednesday sits in the middle of its working week rather than beside a weekend, so it does not create a long weekend on its own. Wednesday 11 December 2030 falls on this day of the week, at the working week's midpoint, three working days deep into the week.
2030 has 365 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.