Parts of NSW’s west had surpassed 45C by lunchtime on Thursday, including Bourke, Cobar and Smithville, while much of the Riverina climbed above 42C.
Almost everywhere else in the state has reported temperatures at least in the 30s – including Sydney’s west, with Penrith, Richmond, Campbelltown and Camden all reaching 35C by 1pm.
The conditions are so extreme that the bitumen on the Oxley Highway near Wauchope, just west of Port Macquarie, began melting about midday.
Walcha Council is using water from a nearby river to cool the pavement.
“Roads and Maritime Services acknowledge water is a scarce resource at this time, however it is required to ensure the safety of motorists and keep the road open,” a spokeswoman said in a statement.
Meanwhile, the NSW Rural Fire Service is battling more than 50 fires across the state – 20 of them are uncontained.
Deputy Commissioner Rob Rogers said 61 new fires were ignited on Wednesday alone, 31 of them started by lightning.
“We’re still trying to capture some of these fires and get them contained,” he told 2GB radio.
Far-western towns of Wilcannia, Menindee and Ivanhoe are all tipped to reach 48C later on Thursday, while some Sydney suburbs are forecast to reach 45C by Friday ahead of an expected cool change at the weekend.
Total fire bans are in place across much of central NSW, stretching from the Victorian border up to Queensland.
Nine places broke temperature records on Wednesday – including six records, according to the Bureau of Meteorology.
Whitecliff, in the state’s northwest, recorded the highest maximum temperature in NSW of 48.2C just before 3.30pm – a record for the area.
Authorities are again warning people to take extra care in the heat by staying indoors, keeping hydrated and limiting physical activity, during the extreme heat.
Paramedics treated numerous patients for heat-related illnesses on Wednesday, including three children in the city’s southwest who were suffering from exhaustion, heatstroke and vomiting.
One was taken to Liverpool Hospital in a stable condition.
Sydney rail commuters are being warned there could be delays across the network as temperatures rise.
Air-conditioned trains scheduled for routine checks have been returned to service, while extra maintenance and medical staff are on standby.