The weather bureau advises "severe" heatwave conditions pose health challenges for vulnerable people, including the elderly, while "extreme" heatwaves are rare events that can be dangerous to anyone not taking precautions to stay cool, and impact on the reliability of infrastructure. While a sea breeze will provide some relief along Sydney's coastal fringe, a "severe" heatwave is forecast for the greater metropolitan area with temperatures in the high 30s and up to 45 in the west on Saturday. Overnight temperatures are expected to remain in the mid-20s in the east of the state, while in the west and far west it won't drop below 30, Mr Shabren said. 15 schools on the South Coast will be closed on Friday, as well as Moruya and Ulladulla TAFE campuses.

Strengthening north-westerly winds preceding and accompanying the front will contribute to elevated fire danger, particularly west of the dividing range – and it's also likely to pick up dust from the state's west and carry it east, along with bushfire smoke, resulting in poor air quality. 'Revise plans' to visit South Coast People planning to head into bushfire-affected parts of the state this weekend, particularly along the South Coast, are advised to "do their research" and revise plans if necessary. Severe to extreme heatwave conditions over most of NSW in coming days. Credit:Bureau of Meteorology

Rural Fire Service spokeswoman Angela Burford said Saturday is shaping up to be the "day of primary concern", with temperatures reaching 40 across much of the state amid areas of strong, predominantly north-westerly winds. "Whilst we’ve had some big wins over the last couple of weeks in terms of containing some of the fires … we've still got a few that we need to keep our eye on and Saturday’s certainly the day of concern for us," Ms Burford said. The heatwave and strong winds pose a risk of spreading existing fires, and starting new fires, she said. There are still 54 fires burning around the state, with one - the Creewah Road fire - at 'watch and act' level.

Three of the state's 21 fire areas have total fire bans for Friday: the Monaro Alpine, Southern Ranges and Southern Slopes. All three, along with eight others are rated at a 'very high' fire danger level. Sydney and most of the area to the north is rated at 'high'. Extreme heat, more fires and poor air could affect people's health. Credit:James Alcock The RFS is most concerned about the Good Good fire burning east of Cooma in the Snowy Mountain area, and the Badja Forest Road fire and Clyde Mountain fire, both in the Eurobodalla region of the South Coast. Small, isolated communities with one road in and out are of particular concern, Ms Burford said. People who don't need to be in those areas should consider revising any plans to go there, and those whose fire plan is to leave should do so early, she said.

"The advice is to plan ahead and be cognisant that there are fires burning in NSW. Revise your plans and do your research," Ms Burford said. "If you are going to travel, set up a watch zone in your Fires Near Me app." A southerly change is expected to drop temperatures as it moves through on Sunday, with potential for thunderstorms and patchy rain into next week. NSW Rural Fire Service community safety officer Marty Webster said people should remain vigilant all along the south coast because "there is so much fire in the landscape". "The forecast is telling us the weather will be worst as you move away from the coast,” he said. "There is danger from existing fires but also there is potential for new fires to start."