Mr Morrison on Sunday afternoon visited the families of NSW Rural Fire Service volunteers Geoffrey Keaton and Andrew O'Dwyer, who were killed on Thursday night fighting fires.

It was the deaths of Mr Keaton and Mr O'Dwyer that prompted the prime minister to announce on Friday morning he was cutting short his overseas holiday.

"(My wife) Jenny and I, our heart broke when we heard of their terrible loss and their great sacrifice and I just want to extend to them our great sympathies, our love and support," Mr Morrison said earlier on Sunday.

The Liberal leader returned to Sydney on Saturday night and on Sunday morning confirmed he'd been in Hawaii with his family on a trip that was planned six weeks ago.

"If you had your time over again and you had the benefit of hindsight we would have made different decisions," Mr Morrison told reporters in Sydney.

"I am sure Australians are fair-minded and understand that when you make a promise to your kids you try and keep it.

"But as prime minister, you have other responsibilities, and I accept that and I accept the criticism."

Mr Morrison said to the people he had upset by being away: "I apologise for that."

He said the focus should now be on the bushfire emergency.

"It's time to be kind to each other," he said.

"This is not a time for division, argument, partisanship or point-scoring. It's a time to support people who have a very important job to do."

The prime minister also acknowledged Australia's firefighters don't want to be out tackling the unprecedented blazes burning across the country.

The PM a fortnight ago said: "The fact is that these crews, yes they're tired, but they also want to be out there defending their communities."

But on Sunday he said: "No-one wants to be out there fighting these fires. No-one wants these fires to be happening at this time. But when those fires do occur, as they have for a very long time in this country, then those who have signed up and put their hand up to be there to defend their communities, then they go out and they do this work."

Mr Morrison said anxious Australians should be very proud they had the best-resourced and coordinated fire services in the world.

The prime minister said he'd always acknowledged the connection between climate change and bushfires but there were also "many other issues" at play, including drought, fuel-load management, lightning strikes and arson.

"There is no argument ... about the links between broader issues of global climate change and weather events around the world," he said at the RFS headquarters in Sydney Olympic Park.

"But I'm sure people equally would acknowledge that the direct connection to any single fire event - it's not a credible suggestion to make that link."

Mr Morrison later visited the Picton Bowling Club evacuation centre with the RFS Commissioner Shane Fitzsimmons, Premier Gladys Berejiklian and state Emergency Services Minister David Elliott.

He spoke with families at the club where about 40 people stayed overnight.

Australian Associated Press