A statewide "code red" alert has been issued for the homeless and most vulnerable ahead of an extreme heatwave across South Australia and eastern parts of the country this week.

Key points: The BOM is expecting temperatures to reach the high 40s towards the end of the week

The BOM is expecting temperatures to reach the high 40s towards the end of the week The temperature is tipped to peak at 44C in Adelaide on Friday

The temperature is tipped to peak at 44C in Adelaide on Friday The SA Government has issued a "code red" for the homeless and most vulnerable

Adelaide is expected to reach or exceed 40 degrees Celsius for four consecutive days, while Broken Hill and Mildura — which is predicted to hit 46C on Friday — are among several locations expecting five such days in a row.

A "code red" means extra accommodation and services will be available for those sleeping rough, including at Adelaide's Hutt Street Centre and Baptist Care SA's Westcare Centre.

Loading

SA Attorney-General Vickie Chapman said the purpose of the code red was to alert all agencies to provide extra services for those who were most vulnerable.

"Also, a high alert to the general community to ring an elderly relative, check on a neighbour and obviously provide support during this time," she said.

"It will be an extreme weather period [and] we will need to do all we can in the community."

Human Services Minister Michelle Lensink said South Australians were not used to dealing with these sorts of temperatures and it was important that extra support was made available.

"In terms of rough sleepers, there are additional services here through Hutt Street [Centre], through services to youth, through Baptist Care and the assertive outreach program, which operates throughout Adelaide's CBD," she said.

"It is a time when people need to take extra precautions, particularly for an extended period."

She said as well as the code red alert, the Australian Red Cross service would be activating its Telecross REDI service from tomorrow.

Ms Lensink said additional services would be made available. ( ABC: Angus Llewellyn )

"That service will phone people wo have been registered as vulnerable and needing a telephone call to check up on them three times a day," she said.

The Hutt Street Centre will be staying open longer throughout the week and will provide meals, water and shelter for the homeless and most vulnerable.

"It's really important that people can seek shelter and can get some relief from the heat because a number of our clients have got some chronic health diseases and health issues," Hutt Street Centre acting chief executive Lynda Forrest said.

"We have been inundated with bottles of water and food and Christmas presents for our clients and their children."

Hutt Street Centre staff members Sofie Thomsen and Peter Mayfield. ( ABC News: Emma Rebellato )

Remote temperatures set to approach 50C

Temperatures in the mid to high 40s are forecast for parts of South Australia, Victoria, Queensland and New South Wales, which is expected to also increase the bushfire risk.

Adelaide's run of sweltering weather will begin on Tuesday and will peak at 44C on Friday before a cool change is expected to bring milder conditions this weekend.

However, temperatures in remote parts of South Australia, such as the Nullarbor Plain, are likely to be significantly hotter and are forecast to approach 50C.

SA's State Emergency Service (SES) also issued a community readiness alert yesterday, advising residents of steps they could take to keep cool and stay safe, and SA Health is also urging people to prepare.

"Heat stroke and heat exhaustion are a real risk. The body struggles to cope with temperatures above 35C," acting chief health officer Chris Lease said.

"People need to monitor their hydration levels."

Dr Lease said pregnant women, children, the elderly and people with chronic health conditions were potentially at the greatest risk.

Bureau of Meteorology (BOM) senior meteorologist Paul Lainio said much of the state was already experiencing temperatures of 40C or above, and that the heat would continue to build.

He said overnight temperatures were expected to remain high as well.

"As you'd expect with such hot days, the temperature just can't really drop very much so … much of the state [will be] experiencing in the mid-20s. Very, very uncomfortable nights," he said.

Mr Lainio said there was also a strong chance that Australia as a whole could record its hottest day this week.

"There's a high possibility that Australia will have its hottest day on record, not only for one day, but possibly four days in a row," he said.

"The hottest day on record previously was 40.3 degrees when you look at Australia as a whole. We may exceed that for a number of days this week."

Loading...