Preparations for Adelaide's third worst heatwave on record are being put in place as the city and other spots get set for five consecutive days of 40 degrees Celsius or above.
The Bureau of Meteorology says Adelaide has only twice had such a run of heat in its recorded history, most recently in January 2009 and before that in 1908, with the temperature soaring above 40C for six days in a row on both occasions.
More than 20,000 emergency service personnel are on high alert, including the Country Fire Services whose crews have already been called into action.
About 40 firefighters are attending a fire in grass and scrub near Stansbury on Yorke Peninsula which has burnt about 20 hectares.
State coordinator Brenton Eden says the fire should serve as a warning to people across the state.
"A fire just started in stubble and straight out of the paddock into local vegetation so it's a timely reminder that if that was in the Adelaide Hills where the houses are spread in among the vegetation there, [there's] much greater risk," he said.
Train services cut to cope with heat
The Transport Department has cut train services to cope with the extreme heat, but trains will run normally on the Gawler, Outer Harbor and Grange lines.
Trains on the Noarlunga line will arrive at intervals of about 15 minutes instead of the usual seven, while some peak services were cut on the Belair line this morning.
The department's Graham Sibery says extra carriages will be put on to maintain capacity.
"If we have a failure and we are trying to work around it, if we've got, let's say 15 to 20 percent less train movements, it's easier for us to get around that failure," he said.
Opposition Transport spokeswoman Vickie Chapman says the new signalling systems for the electric trains are unable to handle the heat.
"It just begs the question how is it possible that we've spent all of this money and we haven't got something that's able to cope," she said.
New heatwave definition includes night temperatures
If Adelaide reaches its forecast maxima this week, it will be the .
John Nairne from the BoM says heatwaves are more severe if there is no respite at night.
"Unlike Adelaide's old definition of a heatwave, we now incorporate the minimum temperature because if the minimum starts higher, we'll be into those hot temperatures sooner," he said.
"That adds to the heat that we're carrying around and also the infrastructure around us and that may actually bring it to the point where it starts to fail."
SA Ambulance service operations manager Anthony Pryzibilla says extra staff and paramedics are on standby.
He says says the workload is not expected to escalate until Wednesday or Thursday as the resilience of vulnerable people wavers.
"When you don't get the cooling effect overnight, people with pre-existing medical conditions can really start to succumb to the heat," he said.
"Dehydration takes an effect which starts affecting the medical condition and the hydration status so that's normally when they start getting into trouble."
The Red Cross has called in about 40 additional volunteers for its Adelaide and Mount Gambier offices to make phone calls to vulnerable people, such as the elderly and disabled.
Executive director Helen Connolly says more than 3000 calls will be made to clients and others who have registered for days of extreme heat.
Hot weather interrupts national junior volleyballers
The National Junior Beach Volleyball Championships have been suspended at Glenelg because of the hot weather.
More than 200 people from around Australia will compete in the four-day event.
Volleyball Australia chief executive Judy Flanagan says matches will only be played in the mornings and evenings when temperatures are below 36C.
"We have a very strong heat policy that we invoke in these situations," she said.
"Obviously the welfare and health of the participants is our number one priority above the competition itself. We will suspend play once temperatures get to 36C and beyond."
© ABC 2014
11:34 EST Canberra is set to see a few mornings drop below freezing as a high sets up over the southeast.