Sydney residents will be forced to endure another muggy night before cool winds bring welcome relief ahead of New Year's Eve festivities.
But nagging low clouds are threatening to spoil views of the harbour city's spectacular fireworks display.
The temperature is only expected to drop to around 24C overnight on Friday, after western Sydney sweltered through its warmest night since February 2011 on Thursday.
Thunderstorms will become increasingly likely on Saturday morning, before southerly winds sweep up the coast and drop temperatures in Sydney to around 28C, according to the Bureau of Meteorology.
"But the impact of that southerly isn't really going to be felt in western Sydney tomorrow unfortunately," meteorologist Rebecca Kamitakahara told AAP.
"They're still looking at another day around 35 degrees."
Showers are predicted to hit Sydney on Saturday afternoon ahead of milder conditions in the evening.
However, there is some potential bad news for the 1.5 million people expected to flock to Sydney harbour to watch the fireworks.
"There will be a fair bit of cloud about and it's possible some of the lower clouds could impact fireworks viewing," Ms Kamitakahara said.
"Although it may not necessarily be wet overnight that could hinder the viewing somewhat."
Showers are expected to hit Sydney for much of New Year's Day, as hot conditions steadily ease over the weekend ahead of a much milder week.
Elsewhere across NSW there is a mixed bag of weather conditions.
Punters north of Sydney are sweating through extremely hot conditions, with temperatures in the high 30s and low 40s, and relief unlikely to come until Monday.
"They're most likely going to have to endure those temperatures through Saturday and Sunday before we get a strong enough southerly change along the coast," Ms Kamitakahara said.
Meanwhile, looming storms could stretch from the northwest to southeast of the state.
"There is potential for them to be severe," Ms Kamitakahara said. "That's for heavy rainfall and damaging winds."
