The temperatures ranged from the high 30 degrees to low 40 degrees in many areas ahead of a cool change sweeping the state.
However, the morning started with fog across parts of the city caused by moisture in the air and higher than average sea temperatures.
It persisted through the afternoon, but the sun broke through and people flocked to Sydney’s beaches and waterways.
The Bureau of Meteorology told 9News.com.au that the highest temperature in Sydney was 40.2C at Badgery’s Creek, in the city’s west, while the temperature at Sydney Observatory in the CBD hit only 28.6C.
Senior meteorologist Jordan Notara said the scorching conditions were caused by a heat trough that moved east and affected all of NSW.
But a cool change will move through from tonight and into tomorrow, with showers and storms returning to south-eastern Australia from Tuesday.
It will see temperatures in Sydney drop to a forecast maximum of 26C tomorrow before the mercury begins to rise on Thursday, with an expected top temperature of 28C.
Much of NSW has endured unseasonably hot conditions over the past three days, leaving more than 30 bush and grass fires burning across the state.
The state’s Rural Fire Service was late today continuing to battle the Yarra Station blaze, burning in the Far West, 100km west of Condo.
It said the fire was burning in thick shrub and spreading in an easterly direction towards Round Hill Road. There were no properties under threat.
And crews were continuing to mop up and blackout hotspots on the Dalgety Rd Fire south of Berridale.
Elsewhere in the country, there are cooler conditions for South Australia and Victoria, but continuing warm weather in Western Australia.
Record heat in NSW sparks bushfires
