If you live in the southern half of Australia, and especially in the southeast, this summer's hottest spell of weather is on its way.

A mass of heat from central Australia will sweep down between now and Australia Day, with temperatures reaching the high-thirties to mid-forties in multiple states on a number of days.

In some areas, maximum temperatures will soar more than 10 degrees above average.

The intensity and persistence of the impending hot weather will see it classified as a severe heatwave for parts of WA, SA, NSW, Victoria, Tasmania and the ACT. Some places will even endure an extreme heatwave, which is the highest category on the three-tiered scale we use in Australia.

So how hot and sweaty are things about to get in your part of the world?

Image: Weatherzone officially recommends this method of coping with heatwaves. Source: Pixabay.

Western Australia

This heatwave will largely byass Perth. The WA capital's hottest weather of the week will be on Thursday and Friday, with tops of 34°C and 36°C respectively, but that's nothing unusual in a month where the average top temp so far has been 33.9 – nearly three degrees above the long-term average.

The heatwave will, however, touch the state's southeast, with Eucla tipped to reach 42°C on Saturday.

South Australia

Adelaide hasn't yet had a 40 degree day this year, which is unusual for almost three weeks into January. But that's likely to change this weekend, with tops forecast of 39°C on Saturday and 41°C on Sunday.

As you'd expect, it will be several degrees warmer in the north of the state, with areas like Oodnadatta – famous for recording Australia's highest ever temperature of 50.7°C in January 1960 – heading for at least five straight days of maximums in the low to mid-forties.

Image: The heatwave will impact all eight states and territories, though Qld and the NT will be only marginally affected. Source: BoM.

Victoria

Remarkably, Melbourne has had only two days above 30°C so far this January. It will miss the worst of this heatwave, with a top of 38°C predicted on Sunday but no other days of very hot weather.

Areas in the north of the state will be much hotter for much longer. Mildura in the state's northwest will likely see three consecutive days of temps of 40°C or higher, peaking at 45°C on Sunday.

Tasmania

There's nothing too drastic in the forecast for Hobart, with several days in the mid-twenties predicted. But the north and northeast of Tasmania could see much hotter conditions, especially around Monday, with temperatures tipped to reach the low to mid-thirties.

ACT

Canberra is heading for tops of 37°C, 38°C and 39°C on Saturday, Sunday and Monday respectively.

That's still a far cry from January 2020, when Canberra recorded its hottest ever temperature of 44°C. But it will be easily the warmest spell to date in a month when the hottest temp has been just 34.4°C .

New South Wales

As ever, Sydney will be hotter in the west than on the coast during a significant heatwave. The city and eastern parts of the city should reach tops of 30°C, 32°C and 33°C on Saturday, Sunday and Monday respectively.

In the city's west, those tops will be much closer to 40°C, and could even reach 41°C in Penrith and other outer western suburbs.

Further west in NSW, a prolonged spell of at least four days of very hot weather can be exected across a wide area of the state, with maximums around or above 40°C in many towns.

And as shown on the map a little higher up in this story, the far south coast of NSW will also cop some extreme heat, with Bega likely to see 42°C on Monday.

And remember...

Severe heatwaves can be challenging for vulnerable members of the community, such as the elderly and those with pre-existing medical conditions.

Extreme heatwaves can also be problematic for anyone who is not taking steps to stay cool, especially people working or exercising outdoors.

So while temperatures in the forties are not exceptional Australia during summer, it's important to note that heatwaves are the most deadly natural hazard in Australia. One study found that heatwaves have been associated with more deaths than all other natural hazards combined.

Stay cool out there, folks.