It has been 75 years since Adelaide has seen such an extraordinary heat wave in autumn, and the weather bureau says there is no relief in sight.

Adelaide is bracing itself for another week of searing heat in the mid to high thirties Celsius.

If Tuesday's temperature reaches one degree more than the expected top of 34 degrees Celsius it will make nine consecutive days of more than 35C.

Duty forecaster Belinda Gibson says such temperatures have not been recorded in Adelaide since an eight-day heat wave in 1934.

"It isn't unprecedented but it's certainly been a long time since we last saw it," she said.

Ms Gibson says there is no end in sight yet to the extreme weather.

The mercury did not dip below 26C overnight and peaked at 32C at 2:00am ACDT.

Temperatures are expected to reach 40C today.