Temperatures have soared across large areas of New South Wales with the heatwave conditions forcing trains to slow down in Sydney and total fire bans in many parts of the state.
People in the capital with respiratory conditions, including asthma, have been told to take care over the next three days after higher-than-normal levels of toxic ozone gas were reported, caused by a combination of the scorching heat, still weather and pollution.
Parts of Sydney saw temperatures as high as 38.8 degrees Celsius, with parts of the city's west experiencing temperatures as high as 41.7C at Sydney Olympic Park and Badgery's Creek reaching 42.8C.
Campbelltown in Sydney's south-west also saw a high of 40.8C.
In other parts of the state, Newcastle reached 36.5C, Cobar saw a high of 39C and Moree broke 41C.
The Bureau of Meteorology has forecast cloudy cooler conditions, showers and possible thunderstorms across the heat-affected parts of the state tomorrow before temperatures climb back up again on Friday.
Sydney Trains put heat speed restrictions in place for Sydney's North, Central and South-West regions.
Speeds were reduced by 10 kilometres per hour, restricting the speed on all lines to 90kph.
A spokesman for Sydney Trains said the restrictions usually applied when the temperature exceeded 39C.
"Extreme heat speed restrictions have historically had very little impact on the punctuality of train services," he said.
Total fire bans
The hot weather prompted the Rural Fire Service (RFS) to impose a total fire ban on the Greater Sydney, Greater Hunter, Central Ranges, Southern Slopes and North Western districts.
"There are some areas getting some unbelievable temperatures," RFS inspector Ben Shepherd said.
"Grass fires obviously will start easily and spread rapidly.
"We're now seeing the introduction of those strong winds. What we don't need now is any fire activity."
Surf Life Saving NSW warned people to stay hydrated and avoid heat stress, with thousands expected to flock to beaches over the coming days.
"Hot weather and school holidays are sure to mean more people will head to the beach or other waterways to try and cool off," Surf Life Saving NSW's Andy Kent said.
"Lifeguards and lifesavers have been extremely busy over the past few weeks and we're urging the public to do what they can to help lessen the load by taking some responsibility for their own safety."
Farmers, livestock feeling the heat
Dairy farmer David Williams said his main focus over the next few days was to make sure that his dairy cows on his Vacy property in the NSW Hunter Valley were well hydrated and had plenty of shade.
"What we try and do is to get them out on the farm early in the morning so they can get access to shade," he said.
"When it's really hot they start panting.
"They've got to have plenty of water."
Mr Williams said lighter coloured animals usually coped better with the heat than darker animals.
"We've got mainly Jerseys [cows] and they definitely take the heat a lot better," he said.
"[The darker ones] are definitely under the shade first."
Mr Williams said the heatwave would lead to reduced to production.
"Because they don't eat as much during the day and their production drops off," Mr Williams said.
"It's a bit harder for them to cool down.
"The thing is to provide them with plenty of good quality food at night when it's cooler."ABC