Earlier this month, temperatures across the ACT had plunged back below two degrees. Now it's on the brink of a four-day heatwave - with Thursday expected to peak at 37 degrees.

Bureau of Meteorology forecaster Helen Kirkup said locals would likely feel a shock to the system during the unseasonable hot spell.

While the bureau had originally issued a severe heatwave warning for Canberra, by Sunday afternoon it had downgraded the alert to low-intensity.

Unfortunately, Ms Kirkup said conditions were still set to worsen in NSW and Queensland where devastating bushfires have been raging for weeks.

The territory will also likely see very high fire danger ratings in the coming days, she said.

"It's been so dry and the ground heats up so much," she said. "A hot air mass over the centre of Australia is coming right across."

Still a fortnight out from the start of summer, close to two million hectares have already burnt in NSW over the past few weeks - that's more than during its past three fire seasons combined.

Six people have died and more buildings have been lost than at any other time in almost a century.

The fires are also wreaking a devastating toll on animals, including livestock. Rescue groups are struggling to keep up with a flood of injured wildlife amid grave fears for already vulnerable koala populations across NSW.

On the ground, firefighters were using the milder weekend conditions to strengthen containment lines ahead of Tuesday's warm weather.

But further north Queensland crews faced storms and erratic winds when hail and lightning hit parts of the state.

Some relief is expected for the weekend ahead, with Canberra at least tipped to drop below 30 degrees by next Sunday.

But ACT firefighters are bracing for a dangerous summer, warning low rain and higher temperatures under climate change are making fires both more frequent and more ferocious.

Nationally, focus has turned to resourcing in recent days, after 23 former fire chiefs said their warning in April about the catastrophic season ahead was ignored by the federal government.

On average in November, Canberra's temperature hovers between a maximum of 22 and 25 degrees.

Its hottest November day on record stands at 39.9 in 2009.

You can support NSW Rural Fire Service by contacting your local brigade or heading to this website.

Or donate to help WIRES rescue injured wildlife in NSW here and the Rescue Collective in Queensland here.

GIVIT is sourcing what people need on the ground in Queensland here.

The Koala Hospital in Port Macquarie is taking donations to set up watering stations for thirsty koalas on GoFundMe here, with additional funds to be put towards a new breeding program to help the species recover.

Red Cross and St Vincent de Paul are also accepting donations for their NSW and QLD bushfire appeals and rescue group Koalas In Care are in need of support.

Rural Fire Brigades Queensland accept donations here.

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