The temperature in Sydney hit a record 45.8 degrees Centigrade (114 Fahrenheit) at 2.55pm today.
As the mercury rose, visiting New Zealanders particularly suffered.
Metro Marker software developer Ben Gracewood tweeted "So amazing. Stepping outside is quite literally like stepping into a sauna. Wall of hot, wet heat. Prickly eyeballs. Crazy but cool."
As he arrived at the airport, Mr Gracewood was asked by NBR ONLINE if he would be willing to kiss the tarmac.
"In Auckland? Definitely," he replied.
Another transtasman traveller, Richard Ram, offered "The 40 degrees yesterday was hot [but] you forget it feels like opening an oven door when you step out from the aircon. Yikes."
The heat has caused numerous problems, including transport delays as overhead wiring overheats.
The annual Big Day Out concert is on in the city today. Patrons have been advised to keep up their fluids.
Relief is on the way tomorrow, with forecasters predicting 25 degrees.