Who gets a public holiday on Monday?

King Charles III is born in November, but most states are taking a public holiday for his birthday this Monday. (Reuters: Dominic Lipinski)

Many Australians are about to have a long weekend thanks to the King's Birthday public holiday on Monday.

The following states have their King's Birthday public holiday on Monday, June 8:

The public holiday for the sovereign's birthday in Queensland is on October 5.

Most of Western Australia has its King's Birthday public holiday on September 28 this year.

But regional cities Karratha and Port Hedland will have their public holidays on August 3.

Last year, Western Australian Premier Roger Cook said his government was looking at aligning the state's public holidays with the rest of the country.

In 2012, the Queensland government decided to move the public holiday from June to October to spread public holidays throughout the year.

A year later, there was a change of government, which decided to change the sovereign's birthday public holiday back to June and shift Labour Day to October.

Then in 2015, a new Queensland government moved the sovereign's birthday holiday back to October and changed Labour Day back to May.

It goes back to a British tradition called Trooping the Colour — and has quite a bit to do with the weather over there.

Trooping the Colour is essentially a military parade that the British Army says dates back to the reign of King Charles II from 1660 to 1685.

"In 1748 it was decided that this parade would be used to mark the official birthday of the sovereign," the British Army's website says.

"It became an annual event after George III became king in 1760."

A parade of this scale is best enjoyed during sunny British weather, compared to a potentially drizzly November day. (Retuers: Toby Melville)

While troops are trained to march in all kinds of conditions, it's generally better for a military parade to be staged during fine, sunny weather — especially if you want crowds of people lining the streets to watch.

And England's winters are notoriously un-sunny, so it was generally best to hold a parade in summer even if the reigning monarch's birthday was in a different month.

"Official celebrations to mark the Sovereigns' birthday have often been held on a day other than the actual birthday, particularly when the actual birthday has not been in the summer.

"King Edward VII, for example, was born on 9 November, but his official birthday was marked throughout his reign in May or June when there was a greater likelihood of good weather for the Birthday Parade, also known as Trooping the Colour