Much of Australia's southeast faces severe to extreme heatwave conditions over coming days, bringing elevated bushfire danger and uncomfortable nights.
A hot air mass that has delivered scorching temperatures across large parts of Western Australia is expected to move across the country ahead of an approaching cold front, the Bureau of Meteorology says.
"The combination of these really warm conditions and also an increase in humidity is going to lead to very warm daytime temperatures and very warm night-time temperatures as well," BoM meteorologist Diana Eadie said on Wednesday.
"As a result we're expecting severe to extreme heatwave conditions to develop across much of the southeast of Australia."
Temperatures exceeded 41C in Adelaide, while Canberra and Hobart cracked 35C by 3pm on Thursday.
Melbourne edged close to 40C, with 38.1C recorded by 3pm.
Griffith in inland NSW reached 41.1C while Cummins in South Australia hit 44.2C. Mildura in northwest Victoria recorded 42.5C.
Ms Eadie said many areas would experience uncomfortable overnight temperatures, including Adelaide where it will not drop below 28C on Friday.
"That's why we're seeing those severe to extreme heatwave conditions because when you don't get those temperatures dropping off overnight, it doesn't allow the body to recover,” she said.
Ms Eadie said the heatwave will bring elevated fire dangers, peaking on Thursday in South Australia, Friday in Victoria and Tasmania, and Saturday in fire-affected areas including the ACT and southern parts of NSW.
She noted humidity levels will be quite high.
"Whilst we'll see those warm temperatures and strengthening winds, it's not as dry as what we've seen with previous events which is why at this stage we're only forecasting severe fire dangers,” she said.
"It's not quite as dangerous as previous situations just because we do have that moisture over fire-affected areas."
Fire danger threatens NSW
Very high and severe fire danger warnings will be in place across NSW over the coming days.
Firefighters are urging communities near blazes in southeast NSW to remain vigilant, with high temperatures lingering through the weekend.
"Elevated fire dangers are set to return over coming days. It is important that you're prepared in the event a fire threatens," the NSW Rural Fire Service tweeted on Wednesday.
Bureau of Meteorology acting state manager Jane Golding said ongoing fires, dry conditions and increased temperatures would increase the bushfire risk.
She said temperatures in central and western NSW would surpass 40C this weekend, making for some uncomfortable evenings.
This is because a system of hot air moving south of the Australian continent will help drag hot air across the NSW coast.
"Broad areas of western NSW, out towards the South Australian border and into the western slopes may not drop below 30 degrees for some nights over the next few days," Ms Golding said in a statement on Wednesday.
"The difference in temperatures for some places from Saturday to Monday will be 15 degrees."
There are currently more than 70 fires burning across the state, while the housing toll for this bushfire season is almost 2400.
The death toll climbed to 25 on Friday when a 59-year-old man's body was found in a NSW south coast home.
Video of the incident emerged online on Wednesday as the men's families visited the Peak View crash site.
The footage shows the C-130 Hercules dropping pink retardant on a bushfire before the tanker disappears into thick smoke and an explosion rings out.
A NSW Police spokesman on Wednesday said the force was aware of the video "and it will form part of the coronial brief of evidence".
NSW Labor, meanwhile, has written to the NSW government requesting that the first sitting day of the parliamentary year is dedicated to the commemoration of the 25 bushfire victims and their families.
In a letter to Premier Gladys Berejiklian, opposition leader Jodi McKay requested the suspension of parliamentary business on February 4 and the movement of a motion of condolence for NSW bushfire victims.
Ms McKay also asked for flags around NSW to fly at half-mast.
"I would be honoured to second this motion and I believe all members should be given the opportunity to speak," Ms McKay wrote.
Heat closes popular walking tracks in Tasmania
Several popular walking tracks have been closed in Tasmania as authorities brace for two days of severe fire danger.
Trails at Freycinet National Park on the state's east coast are among the closures on Thursday and Friday.
The summit of Hobart's Mt Wellington and surrounding park areas are also off limits.
"Although there is no current fire threat to these locations, under hot, dry and windy conditions fires can travel very fast so it is important for everyone to stay informed in case conditions change," the state's park authority said in a statement.
The fire danger will reach severe in the northeast, east coast, midlands and southeast on Thursday, with temperatures peaking in the mid-30s.
It is expected to get even hotter on Friday, with Hobart tipped to reach 38C.
A 48-hour fire ban is in place from 2am on Thursday for the east and south.
No fires can be lit in the open, including campfires, fire pots, incinerators and burn-offs.
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