But Nine News reported that the temperature may have reached as high at 48 degrees in Cambelltown, according to an electronic thermometer outside Campbelltown Performing Arts High School this afternoon.
It was a scorcher right across the city, with temperatures soaring to 46.3 degrees in Richmond, 45.1 in Horsley Park, 44.8 in Holsworthy and 44.5 in Sydney Olympic Park, while the CBD reached a high of 43.4 degrees just after 1pm.
A total fire ban was issued for the Greater Sydney and Hunter regions, as much of the country struggled through the record heatwave.
The NSW Office of Environment and Heritage also warned of higher than normal ozone levels, issuing an Air Quality Forecast alert of poor.
The BoM also issued a thunderstorm warning, with damaging wind gusts of over 90km/h headed for the ACT and western NSW.
NSW residents were warned to protect themselves against heat stroke, ozone pollution and fire dangers as a dangerous "blast furnace" moved across Australia today.
Sydney became the hottest capital in the country early in the day, while large parts of southeast Australia sweltered through the extreme heat with dry, gusty north-westerly winds sending hot air from Central Australia to New South Wales, delivering the searing heat.
It was the "first extreme heat day of the year" across NSW and various parts of Australia, and emergency services were on high alert.
Ambulance Victoria state health commander Paul Holman described the conditions "like a blast furnace".
Meanwhile, Missionbeat program manager Shane Sturgiss told the ABC Sydney's homeless population could be moved to cooler areas to escape the dangerous heat.
"We're particularly concerned for the welfare of older people who might have pre-existing health conditions and long term rough sleepers," he said.
Authorities say the hot conditions are not expected to ease until Tuesday.
"The real issue is that we're not going to see a relief in NSW until early next week, so we're going to see sustained heat over the days and the nights," Deputy Commissioner Catherine Burn said.
A Bureau of Meteorology spokesperson told ABC News this morning that "a weak change should drop temperatures a little bit this evening, but it's quite a short lived change and it will get warm again tomorrow ... it shouldn't get as hot, but western parts of Sydney should see 40C tomorrow again," the spokesperson said.
