Temperatures in New South Wales, Victoria and South Australia climbed toward records in some areas on Monday, with the heat expected to worsen on Tuesday, said Dean Narramore, a senior meteorologist with the Bureau of Meteorology. The mercury could rise as high as 49C in some regions, he said.

“It’s some dangerous weather shaping up tomorrow across southeastern parts of the country,” Narramore said in an interview. “The combination of hot, dry, windy weather will mean that any fires that do get going, or are going right now, likely to become uncontrollable and uncontainable.”

Australia’s southeast is facing the most prolonged heatwave conditions since the devastating Black Saturday wildfires in 2009, Narramore said. Those blazes, the country’s worst, killed 173 people in Victoria.

Extreme weather in recent weeks sparked multiple wildfires – some that are still burning – with authorities warning that hot conditions could elevate the fire danger to “extreme” levels in parts of South Australia and Victoria.

Melbourne was blanketed with thick smoke on Sunday morning from a blaze burning out of control in the Otway Ranges, southwest of the city.