A cool change is slowly moving across NSW after Sydney and regions of northern NSW sweltered through the hottest November night on record.
Parts of Sydney - including the city - broke the 40C barrier for a second consecutive day on Sunday after swathes of western NSW, South Australia and northern Victoria baked through even higher temperatures approaching 45C.
While temperatures have cooled in South Australia and Victoria on Sunday, NSW's eastern and northeastern regions sweated through another hot day.
Maximums in many central Sydney suburbs pushed over 40C again, including Penrith in the city's west.
Temperatures across the Hunter were also well in excess of 40C, with the mercury hitting 41.9C at Cessnock Airport.
A gusty southerly arrived late on Sunday afternoon and is expected to bring cooler temperatures for Monday before the heat returns to NSW from Tuesday.
"That sweet cool relief is finally making its way through Sydney," the bureau tweeted.
"Airport just dropped from 35 degrees to 26 in 20 mins while Bellambi saw a 10 degree fall in 1 hour. Southerly now heading into western Syd and will push into Hunter in coming hours."
Southeast and southern Queensland are also likely to experience elevated temperatures from Monday, with no respite until at least Thursday.
It follows Observatory Hill in central Sydney recording an overnight minimum of 25.3C, breaking the November record of 24.8C set in 1967.
Overnight November minimum records also fell in Camden, Newcastle, western NSW's Bourke and Cobar and Ulladulla on the state's south coast.
Saturday's overnight minimum at Nobbys Head in Newcastle was 24.1C, breaking a 64-year November record of 23.1C.
"The (places) that have the longer records, some of them have been broken, which is reflective of the fact the weather has been rather insanely hot overnight," Bureau of Meteorology meteorologist Helen Kirkup told AAP.
NSW Ambulance's Dominic Morgan said the agency was called out to 3356 emergency incidents on Saturday, its third-busiest day on record.
Total fire bans will remain in place on Monday in NSW's Northern Slopes and North Western districts.
RFS crews battled more than 60 bush and grass fires across the state on Sunday including a blaze in the western Sydney suburb of Northmead which damaged a home.
It was declared under control about 3pm, while another further west in the Blue Mountains jumped to a "watch and act" alert before being downgraded just before 6pm.
RFS Commissioner Rob Rogers said on Sunday the service was deploying "overwhelming force" to attack every major blaze and encouraged NSW residents to have their fire plans ready.
"As soon as we get a fire call, we're sending everything we can to it to limit the spread of these fires," Mr Rogers told reporters.
"Just because we've had some rain in the past few months doesn't mean the risk is eliminated, because it isn't - it's a different risk this year.
"I'd rather not be on the back of a four-year drought, which is what we were in last year ... (we're) definitely better positioned but nonetheless it's a risk."
Last summer's bushfires destroyed 2476 homes and claimed 26 lives.
Australian Associated Press