SA Power Networks has apologised to tens of thousands of South Australian customers who were left without electricity during the state's record heat.

The electricity transmission company has confirmed about 25,000 properties were blacked out when infrastructure began to buckle in the extreme conditions.

Ninety transformers crashed across the state’s transmission network while a substation at Fulham Gardens tripped, leaving 15,000 western suburbs customers without power late yesterday.

“After days of heat, we were in some unchartered territory yesterday with record heat and record load sustained well into the night,” Paul Roberts from SA Power Networks said.

“We understand customers would be inconvenienced by these outages. Given the number of outages affecting small localised groups of 50 to 170 customers, the crews did a great job to restore most people’s power before first light today.

“In terms of what happened, equipment like humans is affected by heat. A number of transformers overheated and their fusing operated as it should to prevent a catastrophic failure,” Mr Roberts added.

Energy Minister Dan van Holst Pellekaan says the government used every tool it had available to prevent forced load shedding yesterday, with the national energy market operator calling on the state’s backup diesel generators for the first time.

“We had enough electricity in South Australia to meet our needs. It was close but we had enough,” Mr Van Holst Pellekaan said.

“The government acted swiftly early and reduced power consumption in its own operations and sites, with the largest contribution from SA Water.

A heat map showing temperatures in SA this morning (l) and the predicted temperature at 5pm today (r). (Bureau of Meteorology)

“We also worked closely with large energy users such as GFG Alliance’s steelworks at Whyalla and Nyrstar’s smelter at Port Pir to reduce demand on the grid,” he said.

The backup diesel generators at Lonsdale and the former Holden plant at Elizabeth were installed by the previous Labor government as part of its energy plan.

Opposition energy spokesperson Tom Koutsantonis urged his successor to walk away from his plan to lease the generators to private firm.

Beachgoers are seen jumping off a jetty at Glenelg Beach in Adelaide. (AAP)

“The switching on of the SA-owned emergency power plant justifies the former Labor Government’s decision to purchase this important asset for South Australians,” Mr Koutsantonis said.

Adelaide soared past 45 degrees today. (AAP)

The Red Lion Hotel will be serving free beer in Adelaide if the temperature reaches the predicted 45 degrees. (Google Maps)

Tasmania is being ravaged by fire, one blaze has been burning since December. (AAP)

A dozen brumbies were discovered dead in central Australia from suspected dehydration. (Alice Springs Community Forum)