'Despicable': Row erupts over bushfires

Firefighters are battling to contain more than 60 bushfires still raging across New South Wales and Queensland before "catastrophic" weather conditions hit tomorrow.

Three people have died and 200 homes and sheds have been lost to the fires so far. Forty blazes remain out of control and a total fire ban is in effect.

Experts are warning the worst is yet to come, with high winds, dry air and temperatures in the high thirties forecast to combine dangerously on Tuesday.

Anthony Clark from the Rural Fire Service said the situation would be "as bad as it gets".

"There's a lot of hard work ahead of us, but the simple message is we're not going to get on top of those fires before these really bad conditions hit on Tuesday," Mr Clark said.

Meteorologist Ben Domensino said a mass of hot air was moving across to the east from Western Australia.

"It is elevating fire danger ratings in South Australia and parts of Victoria today on Monday, then on Tuesday, the threat will shift and focus into NSW and Wednesday, it pushes further north," he said.

"So that's why we're seeing these danger ratings in South Australia elevated fire danger ratings across multiple states on multiple days.

"The drought's been widespread and in some places record breaking.

"We have known this has been coming for months because we've had this dry weather leading up to the hottest time of year.

"Now we're seeing the winds increasing, the temperatures increasing, which are typical of this time of year. But we don't normally have this much fuel."

The conditions are expected to greatly expand the area at risk from "extreme" fire danger. On Tuesday the Hunter, Illawarra and greater Sydney regions in NSW will face that danger. For Queensland, the threat will persist into the following days as well.

There are also fears for residents in parts of Western Australia, with an extreme fire danger forecast for the South Interior.