Thousand of people across Sydney's west have lost power after temperatures climbed to around 45C and the hot, dry and windy conditions prompted the RFS to issue total fire bans across most of the state.
About 5500 people around the lower Blue Mountains are without power and at nearby Penrith a high of 44.8C has been recorded on Friday afternoon, according to the Bureau of Meteorology.
It is much cooler in the city with temperatures near the harbour peaking at 24.7C, but most of NSW is sweltering under the lingering heatwave.
Rural Fire Service Inspector Ben Shepherd says firefighters are on stand-by but the community must be on alert as well.
"We stand ready to respond to any situation, but it's important the community play their part by A, reporting all fires to triple zero and B, having a fire plan in place," he told AAP on Friday.
The heat combined with stronger than predicted winds means a total fire ban is in place over the Greater Sydney Region.
Meanwhile, a severe weather warning has been issued for parts of NSW and the ACT after a storm brought damaging winds which downed trees.
About 500 calls for help had been received by the SES.
In northwest NSW, the record for consecutive days above 40C could be broken at Bourke, which was set in 1892 at 22 days.
After a few days of intense heat, conditions should ease for the southern half of the state during the weekend, a Bureau of Meteorology forecaster told AAP.
But the mercury is set to climb back into the low to mid-40s early next week.
