A heatwave is set to sweep across parts of NSW in the coming days, prompting a warning about the potentially fatal consequences of spending too much time in the sun.
Temperatures are expected to climb into the high 30s and low 40s in western NSW, western Sydney and the lower Blue Mountains over the weekend.
NSW Health says a heatwave in Sydney in 2011 was responsible for the deaths of 96 people and has urged people to keep an eye out for vulnerable members of the community over the next few days.
Warming up ... hot weather is heading to NSW. Photo: Andy Zakeli
"The heatwave that affected Sydney in February 2011 ... is a stark reminder that extreme heat presents a real and potentially life-threatening risk," said NSW environmental health medical adviser Richard Broome.
Dr Broome said heat-related illnesses could affect anyone but certain groups were particularly vulnerable.
These included the over-75s, infants and children, people with a chronic medical condition and people who live alone, he said.
"Heat puts a lot of strain on the body and can cause dehydration, heat exhaustion and heat stroke," Dr Broome said.
"It can also make underlying health conditions worse."
Dr Broome urged people to take precautions during the heatwave, including drinking plenty of water, and avoiding alcoholic or sugary drinks.
He said people should also minimise physical activity and stay indoors during the peak hours between 11am and 5pm.
Anyone showing signs of heat-related illness - including dizziness, fainting, nausea, headaches and loss of sweating - should seek urgent medical attention, Dr Broome said.
Police are also warning motorists about the dangers of leaving children, the elderly or pets unattended in cars.
"There is one golden rule which should never be broken - never ever leave babies, children, the elderly or animals alone in a car even if the air-conditioner is on," said NSW emergency operations controller and acting deputy police commissioner Mark Murdoch.
"It doesn't take long for the temperature inside the car to soar, and for the effects of the heat to take hold," Mr Murdoch said.