AAP
Sydney's heatwave has shattered a 150-year-old record, but the big sweat isn't over yet.
In dozens of suburbs on Saturday the temperature soared into the mid to high 30s for the sixth day running and over much of NSW.
As thousands flocked to beaches and the harbour foreshores to cool off, the mercury climbed above the 38-degree mark while Observatory Hill recorded a peak of 41.5 degrees.
Bureau of Meteorology (BoM) senior forecaster Neale Fraser said that Saturday was officially the sixth successive day that the Sydney area had sweltered in 30-plus temperatures.
Since records were first kept in 1858, Sydney had never experienced such consistently high temperatures.
"We've had runs of hot weather for three or four days but you get a southerly change that keeps it below 30 then it warms up again," Mr Fraser told AAP.
The previous record was five straight days.
Richmond, in Sydney's northwest, broke its own record with seven days straight of 35-plus degree heat.
"And chances are they'll break that again tomorrow (Sunday)," he said.
Mr Fraser said the greater Sydney area might also break the record again on Sunday.
"There's a southerly buster coming tomorrow morning but before that arrives we'll probably hit 30 again," he said.
Temperatures also hit the high 30s and low 40s in suburbs stretching from the Hunter Valley to Illawarra.
The heat led to another spate of bushfires and more health warnings.
The Rural Fire Service (RFS) began battling a blaze at Megalong Valley, in the NSW Blue Mountains, about midday (AEDT).
Emergency services were also fighting a small fire at Morisset on the NSW central coast.
The RFS had already attended more than 100 bush and grass fires this week.
The west/northwest winds also brought high humidity courtesy of Cyclone Yasi that hammered north Queensland, reducing the fire risk.
"The saving grace was the amount of moisture in the air," Mr Fraser said.
Total fire bans were in place on Saturday across the Central Ranges, Greater Sydney Region and Greater Hunter districts.
NSW Health said 62 people had been treated in emergency departments for heat-related illness in the past six days.
The mercury was expected to remain above 30 degrees overnight before the cool change hits southern Sydney around 8 a.m. (AEDT) on Sunday and moves north.
The change is expected to drop temperatures into the 20s.