Sydney's set to have its hottest year in over a century-and-a-half, with the city experiencing its second heatwave in a fortnight.
New South Wales bureau of meteorology says while thunderstorms can be expected in Eastern Sydney on Friday, hot and humid conditions will persist.
Temperatures reached over 40degC in parts of the city on Thursday and, despite rain, look set to continue on Friday with a maximum of 36 degrees.
Police have issued a warning about the extreme conditions, and state government agencies have activated a heat wave action plan, urging people to stay hydrated, avoid alcohol and limit physical activity.
While officials are warning locals to stay indoors, many took the opportunity on Thursday to hit the surf instead. One beachgoer said they "didn't mind the heat".
"We'll just relax and go for a swim every couple of hours, we'll be right," another added.
It's a stark contrast to Melbourne's New Year weather forecast, where there's severe storms and flooding.
The Sydney heatwave put extra pressure on firefighters as they battled over 30 blazes across the state earlier this week.
Despite the "very high" fire danger risk on Thursday, New South Wales rural fire service commissioner Shane Fitzsimmons says the damp air is keeping things at bay - at least for now.
"All this heat is just going to continue to dry out the land, dry out the vegetation."
But with several months still left in the bush fire season, it's not off to a good start.