In Sydney, Australia, the thermometer topped out at 117.14 degrees Fahrenheit Sunday, falling just short of the record-setting 118 degrees that struck the city back in 1939, the BBC reports.
New South Wales Ambulance tweeted that its staffers were also on alert at beaches in the harborside city amid the rising temperatures.
A severe fire danger rating has been issued for the greater Sydney region on Sunday while much of the rest of the state has a "very high" rating.
The sweltering temperatures reached in Penrith were confirmed by the Bureau of Meteorology.
Players participating in the Sydney worldwide tennis tournament were forced off the court at 10:00 local time on Sunday (23:00 GMT Saturday) by the event's organisers after temperatures courtside exceeded 40C.More news: Yogi beef dig at Karnataka CM
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The heat took its toll on French star Kristina Mladenovic, who retired midway through her match citing heat stress.
The hottest Test day on record appeared to be 43.1 degree Celsius in Adelaide in 1908, the Bureau of Meteorology told the Sydney Morning Herald.
Temperatures were expected to remain in the high 30s to early 40s Celsius Monday and the fire ban would be continued, it said.
Numerous blazes had already sprung up on Saturday, with several homes and buildings lost in bushfires in the states of Victoria and South Australia.
Experts have warned that land and sea temperatures have been affected by climate change, leading to more extreme weather conditions.