After its coolest start to the summer in more than a decade, much of South Australia, including Adelaide, is about to finally see some summerlike weather.

Temperatures are on the rise and should peak at 8-12 degrees above average between Friday and mid-next week. Adelaide and the surrounds should experience about four days in the mid thirties, while some of the north and west have at least three days in the forties, something that has not been achieved since last summer.

ECMWF model and BoM forecast temperatures for Tue 12 Jan

A high pressure system which has been anchored south of WA for almost all of the past seven weeks is finally edging east, causing winds in SA to turn from southerly to northerly.

The persistent southerlies which have recently chilled the state have at times led to temperatures being a cardigan-worthy 10-to-15 degrees below average.

ECMWF model and BoM forecast temperatures for 6 Jan 2021

In the first 37 days of this summer Adelaide has averaged 20.3 degrees (combining minimum and maximum temperatures), one-and-a-half degrees cooler than average, and its coolest start to the season since 2001/02.

It has also been the coldest start to the season in 19 years at Coober Pedy in the state's far north, running about three degrees below average.

Wudinna, Port Augusta and Renmark have all had their coolest start to summer in 12 years, running a couple of degrees below the long-term average.