Ferocious heatwave looms for bulk of Australia as system traps hot air over continent

A ferocious heatwave is looming over Australia thanks to a pair of high pressure systems trapping heat on either side of the country.

The heatwave will buffet multiple states, with inland NSW copping the brunt of the "really intense heat", Bureau of Meteorology (BoM) senior meteorologist Miriam Bradbury said.

Twin high pressure systems off the east and west coast of Australia are "recirculating and intensifying" the heatwave and it could mean temperatures climbing well into the 40s across the nation in the coming days.

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While there is some relief in sight for southern parts of the country, Bradbury said inland regions could bear the brunt of the heat into next week.

"Usually the way the weather works in Australia is we might get heat building a little bit, but they will have a strong cold front, sweeping across southern Australia and it'll push that hot air out and away," Bradbury told 9news.com.au.

"What we've seen and will see is that this high pressure is going to hold the heat over the continent and really just recirculate it and intensify it."

Although it will struggle to affect inland regions, a cold front will bring some milder weather in Australia's southern reaches.

"We are expecting a cold front to move across southern Australia from around tomorrow," Bradbury said.

"So that means we're going to see slightly milder weather reaching southern WA and South Australia on Friday, and it will move over Victoria and Tasmania on Saturday."

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The BoM defines a heatwave as when both daytime and nighttime temperatures are unusually hot over a period of three days. 

According to Weatherzone, Oodnadatta, the South Australian town which jointly holds the record for Australia's hottest recorded temperature, is looking at a run of maximums of 44, 45, 46 and 46 degrees from yesterday to Friday.

Other SA locations are also tipped to reach 47 degrees at least once between yesterday and Friday, including Tarcoola, Marree and Oak Valley.

Inland stretches of NSW and Queensland will also reach the mid-40s, with Tibooburra temps tipped to top 45 tomorrow, with the same peak expected for the Queensland town of Birdsville.

With the prediction comes a warning, with the hazardous conditions to last several days.

"When there's one hot day, or a couple of hot days by themselves, most people can manage to deal with that," Bradbury said.

"But when we have really hot conditions, both during the day and at night, persisting for three days, that's when it really starts to take a toll on the body."

The BoM warned all those under the heatwave region should "take the necessary precautions they call stay hydrated, stay indoors".

"Check on family, friends, neighbours and our pets as well to make sure that we're staying as cool as possible," Bradbury said.

With NSW in the crosshairs, the state's health authority has also issued a warning ahead of the heatwave.

NSW Health executive director of health protection Dr Jeremy McAnulty said "people should take extra care to prevent heat-related illness".

He advised the public that to avoid dangerous effects of the heat, people should:

• Avoid being outdoors in the hottest part of the day
• Keep the home cooler by using air-conditioning or electric fans and closing doors, windows, blinds and curtains before it gets hot
• Limit physical activity to early in the morning when it's coolest