Around 30 schools are closed in rural NSW as emergency services prepare for dangerous fire conditions across the state.
Most are primary level in rural areas near Bathurst, Lithgow, and Mudgee, although the Lithgow and Oberon High Schools are also affected.
The closures are due to the extreme fire danger forecast for the central ranges, lower central west plains, and Greater Sydney today due to soaring temperatures and high winds.
A total fire ban will be in effect for the Greater Hunter, Northern Slopes, North Western, Upper and Lower Central West Plains, Central Ranges and Southern Ranges zones from Monday.
The Bureau of Meteorology has issued a heatwave warning, with parts of the state experiencing potentially severe conditions until Wednesday.
Most inland centres will have top temperatures in the mid to high 30s, while Dubbo and Bourke could both reach nearly 40 degrees Celsius.
Nyngan, Coonamble, and Brewarrina are forecast to hit 40 and Walgett and Bourke 41.
"Across much of NSW, we're expecting high to extreme fire danger," said Angela Burford from the NSW Rural Fire Service.
High temperatures combined with strong winds are expected to complicate efforts to deal with any fire activity.
"If a fire does start, it's going to be burning under those difficult conditions," Ms Burford said.
"[It's] harder for our firefighters to get around them, and fire can spread very quickly, particularly in grassland."
Ms Burford said the RFS website and the Bushfire Information Hotline on 1800 679 737 were the best ways to stay up to date.
"If in any doubt, the best option is to not light any fires — it's really important that people remain vigilant throughout the day."
NSW Police were urging people to use common sense and heed the warnings.
"Stay cool and safe around water, but also be conscious of the other risks," Superintendent Greg Moore said.
"We see a spike in misadventure and tragic incidents, such as people drowning or falling from windows or balconies, or children and pets being left in vehicles."
Superintendent Moore, from NSW Police's Incident Emergency Command, said penalties for breaching fire bans could be significant.
"Those penalties are in excess of tens of thousands of dollars or imprisonment."
Superintendent Moore said a fine of $22,000 could apply for leaving a child in a vehicle.
The Bureau of Meteorology says the heat will likely peak tomorrow before milder conditions ease the heatwave by Thursday.