Bathers hit Coogee Beach early on February 10, one of the city's hottest days during a record-breaking summer. Credit:Peter Rae The number of heat-related emergencies had already risen at hospitals across the state during recent heatwaves, NSW Health said. Young men in particular were seeking medical help more often than normal, the department said. More than 1100 people presented to Westmead Hospital's emergency department with possible heat-related conditions in December and January as the city baked in what's likely to be its hottest summer. Emergency staff saw a spike in potentially heat-related conditions including fainting and syncope (a loss of consciousness due to a fall in blood pressure) during heatwave periods.

People exercise at Coogee before the weather heats up. Credit:Peter Rae Most of the state's coast will endure a severe heatwave for the three days from Friday, with parts of the north-east facing extreme conditions, the Bureau of Meteorology said. (See chart below). Power blackout fears for NSW Nationally, debate over Australia's energy security was ignited by outages during a heatwave on Wednesday which cut electricity to 44,000 South Australian households.

The Australian Energy Market Operator (AEMO) worked to avoid a repeat in SA on Thursday and also issued alerts calling for additional generating capacity for NSW on Friday and Saturday. AEMO on Friday morning also issued alerts that Queensland may need additional power supply between 4.30-5pm, local time, which suggests that state may not be in a position to assist NSW in a pinch. The operator also signalled a potential supply shortfall for Saturday afternoon in NSW between 5pm and 5.30pm, local time, and called for "a market response". The minimum reserve available is 696 megawatts, below the trigger for calls of more supply of 700 MW Don Harwin, Minister for Energy, called on the public to help ease the strain: "The NSW government is doing everything we can to ensure a power outage is avoided but we encourage the community to reduce their energy use where possible". As of late on Thursday, AEMO was forecasting NSW electricity demand to reach as high as 14,700 megawatts by Friday afternoon, beating the record demand of 14,600 MW set in February 2011.

"It's going to be a big day," Allan O'Neil, an independent wholesale market analyst, said. The longer the heat lasts, "people are going to give up on any notion of trying to save on their energy bills", and will ramp up their air-conditioners, he said. Saturday will likely be hotter still, with 39 degrees forecast for the city and 45 degrees in western suburbs, the bureau said. Stronger sea breezes are now expected to limit Sydney's maximum on Sunday to 30 degrees, but western parts of the city should swelter again in 40-plus degree heat. NSW Health's Director of Environmental Health, Dr Ben Scalley, said people needed to keep hydrated, stay cool and avoid strenuous physical activity in the heat of the day. Signs of heat-related illness include nausea, vomiting, faintness and dizziness, loss of appetite, weakness, headaches, loss of sweating and reduced urine output. "People showing severe signs of heat-related illness should seek urgent medical attention through their GP or the emergency department at their nearest hospital," Dr Scalley said.

Beck Dawson, Chief Resilience Officer at a City of Sydney-hosted program, said the looming heatwave was probably the biggest test of the summer. "It shows us all the connections across the city", ranging from the viability of transport to schools and hospitals. "Such a long hot period of extreme temperatures across the country may have already killed many of our frailest people," said Associate Professor Adrian Barnett, senior research fellow at the School of Public Health and Social Work, Queensland University of Technology. Fire threat The state's fire crews are unlikely to see much relief as the bushfire threat builds across the state over the coming three days.

Most of the state will face very high fire dangers on Friday, with total fire bans in three southern NSW regions. As winds and temperatures pick up, fire risks will rise further on Saturday, Shane Fitzsimmons, Rural Fire Service Commissioner, said. "On Sunday, winds will continue to increase and if the forecast eventuates, we're likely to see catastrophic fire danger develop in some areas, including the Hunter," Mr Fitzsimmons said, adding that Sydney's threat level is likely to be at least severe if not extreme. NRL club doctors, meanwhile, have said they will cancel matches this weekend if they deem the baking heat is unsafe for players for the opening round of junior representative competitions and NRL trials. The NSWRL has moved some of its matches to start as early as 7.45am, while Canterbury and Penrith's twilight NRL trial at Belmore has been delayed an hour to avoid the hottest part of the day. NSW Police warned the public it was an offence to leave children, pets or the elderly in unattended vehicles, which could have deadly consequences.

NSW Health advised people to avoid drinking alcohol and hot or sugary drinks, close windows and use curtains or blinds to keep the sun out, wear a hat and sunscreen when outside. People who did not have air conditioning are advised to spend time in air-conditioned places like shopping centres, a library or cinema. Transport for New South Wales is also encouraging commuters to avoid travelling during the hottest parts of the day, carry water with you and if you feel unwell, don't board the train, bus, light rail or ferry.