But when it comes to the 2019-2020 bushfires, it's a word that should no longer be used as an excuse for lack of action, or inadequate response.

The fact that the horror summer seemed to come out of the blue is as much of an alarm bell as the weather itself. This was one of the many messages behind the findings of the Royal Commission into National Natural Disaster Arrangements, handed down Friday.

The hearings lasted six months, with 1750 public submissions and nearly 80,000 pages of documents.

Unprecedented indeed, but, said royal commission chair Mark Binskin, "unprecedented is not a reason to be unprepared".

"We need to be prepared for the future. The national natural disaster arrangements Australians deserve require unity, not just of commitment or purpose, but of action," he said.

"Only then can Australians have confidence that the arrangements are the best they can be. The time to act to improve arrangements is now."

The commission found the Commonwealth government must play a larger role in responding to future natural disasters and that there needed to be greater leadership from the federal government during national disasters, despite states holding the primary responsibility for emergency management.

Implicit in all the findings was that the link between fires and climate change is becoming increasingly apparent, and the government needs to get serious on climate change if it is serious about reducing the impact of such devastation.

Extreme weather events, like those of the summer, are likely to become more frequent, and the country needs to accept this and be prepared, rather than prevaricating over the extent of human responsibility that needs to be taken into account when formulating a response.

The proverbial holiday - Scott Morrison's Hawaiian jaunt notwithstanding - is over, and the country - and the world - need to be ready.

The findings made for a particularly grim picture of the future. The commission heard from the CSIRO that some degree of climate change was "locked in" over the next 20 years because of existing emissions.

This has been a year like other, topped by a summer like no other. But, unlike the coronavirus, climate-related catastrophes were foreseen, and warned about. It's time now to make them part of the "new normal" - another overused term.

But overuse is often the only way to bring the message home.