South Australian hospitals have treated more than 50 people for heat-related illnesses on the state's third day of extreme heat, as temperatures soared above 46C.
SA Health reported 51 heat-related presentations to emergency departments in the 24 hours to 3pm on Friday, with 15 of those admitted to hospital for further treatment.
The temperature in Adelaide hit 42.2C just before 1pm on Friday, while the regional centre of Port Augusta reached 46.4C just before 2pm and the small town of Roseworthy, north of Gawler, reached 45.8C shortly after 2pm.
The conditions prompted the Australian Energy Market Operator (AEMO) to issue a lack of reserve notice for Friday afternoon, but SA Energy Minister Tom Koutsantonis said it's unlikely the state's backup generators will be needed.
"There are many stages of lack of reserve notices," he told reporters on Friday morning.
"If we get to the point where we need to step in, we have a state-owned generator that can step in quickly and respond within minutes and we have a battery that can step in within seconds."
The forecast forced the cancellation of the Bupa Challenge cycling event, where thousands of recreational cyclists were due to ride the Tour Down Under route.
Despite the cancellation and warnings from authorities including SA Health, South Australian police said many had flouted advice and rode the course.
Food, mechanical support, first aid, timing and medical services were cancelled, but police worked with paramedics to monitor the safety of those who chose to ride.
The RSPCA reminded pet-owners to be vigilant during the heat, and said extra steps must be taken to ensure the welfare of animals.
"Don't take pets away from home unless absolutely necessary - it increases stress and the likelihood of them becoming dangerously hot, and where possible move your pets inside," RSPCA SA chief inspector Andrea Lewis said.
A change moved across the far west of the state on Friday, but Bureau of Meteorology forecaster Matt Collopy said it would bring little relief to the city.
"It will take quite a while to displace the really hot air that we're seeing across the greater Adelaide area," he said.
"It's not a proper cool change with a nice burst of southerly cold air coming off the southern ocean, it quite a weak south to southeasterly change."
Some relief should reach the city by the weekend, with the maximum temperature predicted to be a more tolerable 35C on Saturday and 34C on Sunday.
