Australia Weather News

Scorching temperatures around NSW this weekend are set to provide a "shock to the system" after a cool summer.

Mild conditions are about to be replaced by severe to extreme heatwave conditions as a hot airmass is pulled across western and southern parts of the state.

Daytime temperatures are expected to be well above average on Friday, with the mercury tipped to reach between 35 and 45 degrees Celsius through Sunday and Monday in inland parts of NSW.

Western Sydney is forecast to reach 38 to 40C on those days too.

Sydney's CBD was forecast to hit 32C on Friday and Sunday.

The Bureau of Meteorology's (BOM) Gabrielle Woodhouse said although records weren't expected to tumble, the hot weather would be a departure from recent cool temperatures.

"We haven't really been experiencing this kind of heat, compared to say last summer when we were having this heat fairly regularly," she said.

"It's going to be a bit of a shock to the system for many people, so it is quite significant because we haven't been seeing these temperatures recently."

Ms Woodhouse said temperatures would be between "8 to 16 degrees above average in places" and would elevate the risk of fires.

Far north-eastern parts of the state will largely miss out on the heat, while coastal areas will be cooled by sea breezes.

Ms Woodhouse said forecasting Australia Day was a "'difficult one".

"At this stage we're looking at a few showers developing in the afternoon and into the evening on Australia Day through the eastern parts of New South Wales."

Health warnings as temperatures soar

NSW Health Acting Director of Environmental Health Aditya Vyas warned people to take extra case to prevent heat-related illness.

"Hot weather puts a lot of strain on the body, including dehydration, and can make underlying health conditions worse," Dr Vyas said.

"Protect yourself during the heatwave by postponing or rescheduling your outdoor activities.

"Reduce the impact of heat by avoiding being outside during the hottest part of the day; keeping well hydrated with water; and looking after vulnerable neighbours and relatives."

Dr Vyas said if people were trying to beat the heat at shopping centres, it was important to maintain COVID-safe practices, such as physical distancing and wearing a mask.

Surf Life Saving NSW CEO Steve Pearce said this was "the weekend" lifesavers had been looking out for.

'We're going to have a convergence of people coming down to the beaches because it's going to be extremely hot," he said.

Mr Pearce said "challenging swell conditions" from the past few days would continue to pose a problem for even the best of swimmers.

"This coming period, over the next four days with this heatwave, we're expecting to be extremely operationally busy."

Mr Pearce said this weekend he was also on alert for alcohol-related drownings.

"It's going to be extremely hot, people are going to be looking to hydrate … but don't try and hydrate with a beer or a chardy."