"El Nino, which is characterized by a warming of the tropical waters in the Pacific Ocean, brings warmer and drier conditions to much of Australia, especially in the southeast," Miller said.
January is typically the hottest month of the Australian summer, and many fear the early heatwave may be the prelude to even more extreme weather in early 2019.
Sydney endured its hottest temperature in nearly 80 years in January 2018, with the mercury rising to 47.3 C (117.14 F) -- just half a degree off the all-time recorded high of 47.8 C (118.04 F) in 1939.
Super-high temperatures at the start of this year put a big strain on wildlife, with thousands of flying foxes dying due to dehydration, while an unusually hot and dry winter saw severe droughtshit part of the country in August.
Even as Australia has suffered the effects of ongoing climate change, the government drags its feet on crafting a comprehensive environmental policy.
Despite a report from the Intergovernmental Panel on Climate Change warning of "global catastrophe" should world temperatures rise above 1.5 C by the middle of the next decade, Prime Minister Scott Morrison's administration has refused to phase out the use of coal-fired power.
"I'm very much supportive of the coal industry," Deputy Prime Minister Michael McCormack told Sky News in October.