Qld, NSW outback towns to reach high 40s as heatwave sweeps across eastern Australia

The heatwave as it moves across Australia on Friday, with the red part representing temperatures above 45C. Photo / Bureau of Meteorology

Temperatures in parts of New South Wales Queensland are tipped to climb as high as 48C in the next week as Australia's long, hot summer gets longer and hotter.

An extreme heatwave will sweep across the country's east this weekend, with northwest NSW and south west Queensland bearing the brunt.

Birdsville, in Queensland's far west is tipped to reach 48C next Tuesday.

The outback town has sweltered through extreme temperatures, with just one day below 40C since January 15.

Night-time temperatures have barely dropped below 30C.

On the same day Birdsville hits 48C, the outback NSW town of Bourke is also tipped to reach 46C.

The town has had a week of temperatures in the low to mid 40s and NSW Bureau of Meteorology forecaster Jordan Notara said a cool change was a log way off.

"Really there isn't any major relief for the western arts of NSW and the north west," he said.

Sydneysiders, fresh from the hottest January on record, are again set to swelter with the brief respite of cooler days and nights set to end on Saturday.

The mercury will drop to only 24C overnight Friday, and climb as high as 36 degrees on Sunday, according to the Bureau of Meteorology.

North of the border, temperatures in South East Queensland will remain fairly consistent over the weekend and into next week as the heatwave sweeps through, with temperatures in Brisbane and on the Gold and Sunshine coasts tipped to reach the low 30s for the next few days.

Queensland Bureau of Meteorology forecaster Rick Threlfall told the Courier-Mail the sustained heatwave in Queensland is unusual.

"Normally you get a heatwave for a day or two before a cool change comes through," he said.

"But there's no sign of any cool change until next week.

"It will get gradually hotter and hotter each day."

Applethorpe, in the state's mid-south Granite Belt, had its hottest February day since records began on Thursday, according to the bureau.

The mercury reached 36.5C on a February day for the first time since records began in 1967.

The heatwave will only impact NSW and Queensland, with temperatures throughout the rest of the country staying relatively mild this weekend.

Though Melbourne's temperature is forecast to reach 35C on Saturday, it will quickly drop back to 27C on Sunday and then a cooler 18C on Monday, before beginning to climb again midweek.

Adelaide will mostly reach the high 20s throughout the weekend, with a brief drop to 22C on Monday, before temperature in the South Australian capital begin to rise again on Tuesday.

There is a forecast high of 36C for the city on Wednesday.

In Perth, temperatures will remain in the mid to high 20s throughout the weekend and into early next week, while Hobart will have temperatures around the low to mid 20s.

The Top End is in the midst of cyclone season, and Darwin is expected to be hit with monsoonal rains this weekend.

According to the bureau, the monsoon is lying near the north coast and gradually strengthening.