Parts of Australia, like Sydney, sweltered with temperatures expected to remain high on Sunday through the hottest November night on record, leading authorities to impose a complete fire ban.

On Saturday, Sydney CBD approached 40 degrees Celsius (104 F) while western New South Wales, South Australia, and northern Victoria baked at even higher temperatures of close to 45 degrees.

Temperatures are forecast to reach 40 degrees on Sunday for a second straight day, while a five or six-day heatwave has been projected by the Bureau of Meteorology for parts of northern New South Wales and southeast Queensland.

The forecasts for rising temperatures prompted the Australian Energy Market Operator (AEMO) to claim that on Sunday afternoon, demand may surpass supply in New South Wales.

With last season dubbed 'Black Summer' by Prime Minister Scott Morrison, Australia has been experiencing hotter and longer summers due to unusually prolonged and intense bushfires that burned almost 12 million hectares (30 million acres), killed 33 people, and an estimated 1 billion animals.

For most of eastern and northeastern NSW, the Rural Fire Service issued a complete fire ban for Sunday, saying there was a very high to severe fire hazard forecast" as strong gusty winds worsen dry conditions.