Revealed: Why Australia’s summer nights are getting hotter

Records for warmest overnight temperatures keep on being broken this summer. See why it’s happening – and what you can do to get a good night’s sleep, even in the heat.

Struggling to sleep? You’re not imagining it. Nights really are getting warmer, with Bureau of Meteorology figures showing minimum temperatures in January were more than two degrees above average in New South Wales, Victoria, Queensland and South Australia.

Locations around the country have set new records this summer for minimum temperatures.

Birdsville soared to a brutal 49.4C on January 25, but there was no respite for locals after sunset, with the mercury dropping only to 36.4C overnight, before it climbed again to 46.1C on January 26. The overnight “low” set a new record for Queensland, and it was the second-hottest night-time temperature ever recorded in Australia. (The hottest was 36.6C in far northwest NSW in 2019.)

The Bureau of Meteorology’s annual climate statement, released on Thursday, showed that mean minimum temperatures were above average for all states and the Northern Territory in 2023.

And it’s not just an Australian problem, said climate lecturer Sarah Perkins-Kirkpatrick.

“Since the mid 1950s we’ve seen quite a significant trend in the intensity and frequency of warm nights, pretty much everywhere,” the Associate Professor from the University of NSW said.

“There’s a lot of evidence that minimum temperatures are increasing faster than maximum temperatures, basically everywhere in the world, and Australia is no exception to that.”

The reasons why nights are not cooling down vary, Assoc Prof Perkins-Kirkpatrick said.

“In some seasons it’s because we’re having lots and lots of heatwaves and there’s lots of heat that simply cannot escape during the nighttime, but for this season a lot of Australia has had a lot of rainfall, and with rainfall comes clouds, and clouds act like a blanket – especially at night, so we don’t get those lower temperatures because those blankets are basically trapping any energy within the atmosphere,” she said.

Associate Professor Sarah Perkins-Kirkpatrick. Picture: Supplied

Adelaide GP Dr Kate Wylie from the group Doctors for the Environment. Picture: Supplied

Besides making it difficult to sleep, warmer night-time temperatures also pose a problem for firefighters, as bushfires don’t die down in the way they once did, while health services face a greater strain because of increased illnesses.

“Normally our bodies will cool down overnight, and hotter nighttime temperatures puts extra stress on our system,” executive director for the group Doctors for the Environment Australia, Adelaide-based GP Dr Kate Wylie said.

That extra strain can result in heart attacks, strokes, renal failure and urinary tract infections (because of extra strain on the kidneys) as well as a host of mental health problems, including depression, anxiety and increased suicidal ideation, Dr Wylie said.

Originally published as Revealed: Why Australia’s summer nights are getting hotter