Thursday's searing conditions, more akin to the height of summer than mid-autumn, will likely have set a slew of site records across south-east NSW and far-eastern Victoria.
These will add to the series of April or late-season records collected across southern Australia over the past week.
Craig Ryan, a meteorologist from the Bureau of Meteorology, attributed Thursday's bout of heat to a high-pressure system that has "built up for some time".
The lack of onshore winds was a factor in the high readings along the south-east tip of Australia on Thursday, he said.
Places with outstanding maximums on Thursday included 35.4 degrees in Bega and 36.1 degrees on Gabo Island in Victoria.
The latter compared with a previous April record of 35 degrees set during on April 4, 1986, and was the hottest at Gabo Island in any month since January 2006, Blair Trewin, senior climatologist at the Bureau of Meteorology said.
South of the border, east Gippsland included 37.2 degrees at Mallacoota, about 17 degrees above the April average for that site.
Some relief is several days off.
After Friday's heat, Saturday's top for Sydney is forecast to be 30 degrees. If reached, that would make it five days this month of 30-degree weather, compared with an average in April of just 0.4 such days.
A front will move across NSW over the weekend, bringing some rain to inland regions, Mr Ryan said.
Sydney is unlikely to get more than a shower on Saturday morning, with perhaps 1 millimetre falling. Most of days next week will also be dry, although temperatures will at least moderate to the mid-20s most days.
The abnormally warm autumn could extend well into May, according to the bureau's three-monthly outlook, released on Thursday.
The odds favour most of Australia experiencing above-average daytime temperatures for next month.
The current unseasonable warmth "appears to be driven by high ocean temperatures, and weaker westerly winds and much lower than average soil moisture across southern Australia," bureau specialists said in an article published in The Conversation on Thursday.
Farmers – and firefighters, who were active in NSW and Victoria on Thursday – will be hoping the bureau's prediction of above-average rainfall in parts of eastern Australia will come to pass.
Peter Hannam is Environment Editor at The Sydney Morning Herald. He covers broad environmental issues ranging from climate change to renewable energy for Fairfax Media.
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