Much of Australia is baking through the hottest spring weather in years this week as temperatures surge as much as 13°C above average.
Midweek maximums peaked well above 40°C across the outback, including 45°C in Birdsville (QLD), Wilcannia (NSW), and Moomba (SA) – all four-year state highs for spring.
But the hottest town has been Roebourne in WA’s Pilbara, where a high of 46°C last weekend was the highest spring temperature anywhere in Australia since November 2020.
On the opposite side of the country, Bushy Park’s top of 31°C on Wednesday was the highest Tasmanian temperature in four years.
Our capitals are also feeling the heat, with both Melbourne (Wednesday) and Sydney (Thursday) climbing above 30°C and sweating through their hottest days since March, while Brisbane faces a muggy 33°C on Friday.
The burst of hot weather across the country is an extension of an ongoing heatwave over northern Australia, offering a sneak preview of a summer that is likely to be one of the warmest on record.
Friday scorcher for Sydney and Brisbane
This week’s summery conditions are the result of a stagnant high-pressure system a few kilometres above the surface, often described as a “heat dome” by meteorologists.
Under a heat dome, air sinks towards the ground where it compresses and warms up – and during extended spells of descending air, a heatwave forms as skies remain sunny and the dome prevents cooler surrounding air from mixing in.
This set-up allowed a broad mass of very hot air to form over tropical and central Australia this month, which was then transported south by a northerly airstream to also bring a short spike in temperatures to south-east states.
While a cooler southerly has now flushed the heat out of SA, Tasmania, and Victoria, hot weather will continue across north-east Australia on Friday, along with the NSW coastline.
Sydney is forecast to again reach 30°C, while Brisbane’s forecast of 33 is already the city’s fourth day above 30°C this month, part of a severe heatwave developing over south-east Queensland.
The heat also brings a heightened risk of bushfires, with high fire dangers predicted on Friday across most of WA, NSW and Queensland, although winds are below the speeds required for an extreme fire danger, even with maximums well above 40°C.
Heatwave to linger this weekend and summer scorcher tipped by BOM
Cooler onshore winds will lower temperatures near the NSW coast by the weekend, however much of northern Australia, including south-east Queensland will continue to swelter through daily highs well above average.
Cooler maritime air will lower south-east Queensland’s temperatures by Monday, but the change will fail to penetrate the inland heat dome, resulting in ongoing maximums well above 40°C across the northern interior.
The ongoing heatwave may even break records for longevity, for example Longreach in central Queensland has now sweat through six consecutive days above 40°C and is forecast for at least another seven, which would equal the current record of 13 spring days above 40°C from 2014.
So when can northern Australia expect relief? Modelling is indicating it could be a week until the heat dome breaks down, when a combination of cooler southerly winds through the interior and an increase in cloud cover in general over the tropics is able to slowly lower temperatures back to normal.
For southern states, there are currently no indications of hot weather returning next week, however as summer fast approaches, the latest seasonal modelling is doubling down on earlier forecasts of well above average temperatures.
The Bureau of Meteorology’s latest update of their seasonal outlook is predicting Australia will be about 1.5°C warmer than the long-term average (1961–1990), enough to comfortably place this summer’s temperatures in the top five since 1910.
Nights this summer are tipped to be especially muggy with a greater than 70 per cent chance of minimums in the hottest 20 per cent of years for the whole of northern Australia and most of the eastern seaboard.
The confidence is partly climate change, but also the current state of the oceans surrounding Australia.
Water temperatures are higher than normal off nearly every coastline, and are simmering up to 3°C above normal offshore from northern WA.
The warm water will not only raise the temperatures of the surface air over the ocean, but can also promote higher humidity – which then leads to higher minimums as temperatures struggle to fall overnight when moisture levels are high.
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