NSW is set to sizzle over the coming days with the state facing scorching temperatures and potentially catastrophic fire danger.
Total fire bans and extreme or severe fire danger warnings are expected in parts of NSW on the weekend, the Rural Fire Service said on Thursday, with temperatures tipped to rise as high as 48C.
"If the forecast eventuates we're likely to see catastrophic fire danger develop in some areas including the Hunter," RFS Commissioner Shane Fitzsimmons said in a statement.
RFS Inspector Ben Shepherd said recent heat has dried out substantial parts of NSW.
"In the next few days we're likely to experience some of the highest fire dangers for this season," he told AAP.
The blistering conditions could see Sydney's CBD record 38C on Friday while 44C is forecast for western Sydney.
The bureau is predicting 39C in the city and 45C in the west on Saturday with lower maximums likely on Sunday.
Hardest hit will be towns in the state's far north and west including Bourke and Ivanhoe - tipped to reach 47C and 48C on the weekend.
The Hunter region will also struggle to cope with 45C heat through the weekend, with Singleton and Cessnock topping the predicted temperatures with 46C on Saturday.
The Australian Energy Market Operator is forecasting a record demand for power in NSW on Friday reaching 14,700 megawatts.
Demand will likely peak between 4.30pm and 6.30pm.
"The NSW Government is doing everything we can to ensure a power outage is avoided but we encourage the community to reduce their energy use where possible," Energy Minister Don Harwin said in a statement.
Electricity demand could jump by 50 per cent in western Sydney, according to Endeavour Energy, which will place emergency crews on stand-by in case of network faults.
Ausgrid has cancelled scheduled maintenance work in the Hunter Valley and other areas forecast to reach 40C or higher.
"The main difference with this particular heatwave is there is a significant change in the wind speed and direction," Insp Shepherd said.
"It's likely that we'll see stronger northwesterly and westerly winds and it is expected to be drier than normal."
The scorching conditions will arrive just days after Sydney received half-a-month's average rainfall in one day on Tuesday.
However, relief may be on the way sooner than previously expected, with forecasters now predicting a cool change in some areas of the state on Sunday morning.
"We are looking at a fairly early southerly change on Sunday - that could drop the temperature down quite a bit," Bureau of Meteorology forecaster Andrew Haigh said.
Parts of the coast and greater Sydney are due to cool down to the mid-20s on Monday and Tuesday.
The RFS is urging residents in bushfire-prone areas to have evacuation plans in place and to keep track of the organisation's website or the Fire Near Me app for updates.
