Posted by 
Almost half of Australia is blanketed by a heatwave today as the mercury starts to climb before an expected peak on the weekend, with heat records set to be broken in some parts.
Residents in western Sydney can expect a top temperature of 38 degrees, before the mercury hits a scorching 42 degrees tomorrow, in what forecasters say will be the hottest in four years.
The last time western Sydney recorded temperatures of 42 degrees or higher was during the Black Summer of 2019-2020, according to Weatherzone.
READ MORE: Powerful magnitude 7.1 earthquake shakes Vanuatu
Other parts of New South Wales can expect temperatures of 40 degrees or more today. Wilcannia in the state's west should reach 46 degrees, Walgett on the Northern Slopes will have a top of 43 degrees and at Wellington in the Central Tablelands the mercury will peak at 40 degrees.
The state's Rural Fire Service has issued a total fire ban today for the Lower Central West Plains, Southern Riverina, Northern Riverina and South Western areas.
Residents can expect some relief late tomorrow with the chance of thunderstorms.
Temperatures on Sunday are forecast to fall to the mid-twenties.
Meanwhile, firefighters in South Australia are bracing for the worst fire conditions in four years, which will be followed by more than a month's worth of rain on the weekend.
Temperatures are expected to soar into the mid-40s in some parts of the state today, while wind gusts are predicted to reach up to 90km/h and widespread dry lightning.
READ MORE: Ferocious heatwave looms for bulk of Australia
In an update today, the Bureau of Meteorology said the following areas of the state will experience damaging winds in coming hours: Eastern Eyre Peninsula, Flinders, Mid North, Riverland, Murraylands and parts of Mount Lofty Ranges, Yorke Peninsula, North West Pastoral and North East Pastoral districts.
Dry lightning will create a risk of fires starting anywhere thunderstorms occur.
The Commonwealth has flown a large Boeing 737 airtanker into the state to provide the state's firefighters which will bolster the state's additional aircraft fleet.
In Victoria, the worst of the heat will be felt in the state's north west.
Both Mildura and Swan Hill are heading for a top temperature of 45 degrees today before a south-westerly change brings relief later.
The BoM defines a heatwave as when both daytime and nighttime temperatures are unusually hot over a period of three days.
The BoM warned all those under the heatwave region should "take the necessary precautions they call stay hydrated, stay indoors".
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
Sydney's hottest suburbs during summer hot spells are usually low-lying suburbs, such as Penrith and Richmond on the Hawkesbury-Nepean floodplain at the foot of the Blue Mountains.
That will again be the case this Saturday, with both suburbs expected to reach 42 degrees.
The city and coastal areas of Sydney are tipped to be less stifling due to a cooling sea breeze but it is difficult to forecast when that will kick in.
Currently, the city is predicted to reach 38 degrees, but it could top 40 degrees depending how things develop.
Whatever happens temperature-wise, it is certain Sydney's pools and beaches will be packed with residents seeking relief from the scorching conditions.
READ MORE: Tropical Cyclone Jasper intensifies into severe storm
Elsewhere in Australia, residents in every mainland state have been warned of heatwave conditions, with temperatures forecast to soar upwards of 40 degrees.
Twin high pressure systems off the east and west coast of Australia are circulating the heatwave and it could mean temperatures climbing well into the 40s across the nation in the coming days.
The BoM warned all those under the heatwave region should "take the necessary precautions they call stay hydrated, stay indoors".
