Sydney – and much of southern Australia – is likely to get its biggest blast of heat since last summer by early next week.
Updated forecasts on Friday evening pared back Sydney's expected tops next Tuesday and Wednesday to 31 and 33 degrees, still the warmest pair of days since January.
Places in the city's west such as Penrith and Richmond should still be singed in 37-38 degrees for those days.
Meteorologists had been looking at the prospect that the four south-eastern cities of Adelaide, Melbourne, Canberra and Sydney could reach 33 degrees next Tuesday.
The last time each of the four centres hit that mark on the same day was in February 2011, and in December that four-city result hasn't been recorded for 51 years.
"It's rare to have all of those cities reaching those kind of thresholds all at the same time," Rob Sharpe, a meteorologist at Weatherzone, said. .
The burst of warmth comes after large parts of inland NSW and Queensland were scorched in a persistent heatwave last week.
"The intensity of the hottest air is fairly similar [to that heatwave]," Mr Sharpe said. "It's just across a larger area", bringing consecutive days of warm conditions to much of southern Australia.
For Sydney, a mild couple of days with close-to-average maximum temperatures of about 26 degrees will make way for some hotter conditions that point to even severe heatwave conditions for the NSW coast by early next week.
(See Bureau of Meteorology's updated heatwave chart below for Monday-Wednesday.)
Overnight conditions could be sticky next week, with a minimum of 23 degrees predicted for Wednesday morning.
At least the city should get a five-day reprieve from thunderstorms before the cool change arrives.
Next week's warmth "is a taster for what's coming later in the season", particularly in eastern Australia, Mr Sharpe said.
"People in the east should gear up for a fairly hot end for December and across January," he said.
Sydney's day-time temperatures so far this month are running at about three degrees above the long-run average, while overnight lows are about two degrees warmer than normal.
