South Australia has sweltered through a day of extreme heat with temperatures in some regional centres pushing into the mid-40s.
The mercury also topped 43C in parts of Adelaide on Thursday with another day of high temperatures to come before relief on the weekend.
Bureau of Meteorology senior forecaster Kylie Egan said two troughs were moving across the state, and would bring significantly cooler temperatures to the coastal, southern and mid-north districts on Saturday.
Areas in the north of the state could expect the heatwave conditions to continue for another week.
"The trough pushes into the northeast of the state through the weekend, so most of the state for the week ahead of us are looking to be on the mild to warm side," Ms Egan said.
"But as soon as you get further north into the Flinders or pastoral districts, conditions up around 40 degrees plus will continue for a few more days."
In Adelaide, the mercury hit 43.7C at the bureau's Kent Town weather station but pushed slightly higher in the city's northern suburbs.
By Saturday the city's top should fall to a more pleasant 30C with 28C forecast for both Sunday and New Year's Eve.
But Ms Egan said longer term there were already signs of the heat building again.
"These troughs or changes that are pushing through are really quite shallow," she said.
"So the heat is just being pushed around the country.
"It looks like we could see some heat returning to the state mid-to-late next week."